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Solid States Devices => solid state devices => Topic started by: Farmhand on June 11, 2014, 06:13:29 PM

Title: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 11, 2014, 06:13:29 PM
Hi all, I found that this circuit works ok for boosting from a "single cell type voltage" to over 5 volts,
I can charge 3.7 volt cells with it.

This circuit is a variation of the "Stingo" circuit, I simply used a capacitor in series with the upper pnp transistors base and
used a variable resistor across the capacitor to adjust the frequency/power.

Feel free to share any single coil "feedback" type oscillators here.
..
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Vortex1 on June 11, 2014, 06:43:58 PM
This is the elementary schematic for the circuit I posted some time ago. I have not included values as they will change over a wide range depending on the application.

There are many enhancements to this circuit that are valuable. I will post them in time.

Note that the "stingo" circuit is different in that the pnp is connected C-E in reverse in most all of the google images I have seen. I don't know how that can work, but I haven't tested it yet. Is this an error by Sucahyo?

The schematics I posted are shown as led pulsers but can be simply converted to boost converters in the usual manner.

Note: For operation, a current limiting resistor should be in series with R1 or R3 so as not to blow the npn B-E junction at an extreme pot setting.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 11, 2014, 07:07:09 PM
Yeah Vortex I think you're right, it looks like a mistake in the Sucayho drawing.

Here is the wave forms produced at the NPN collector in yellow and the NPN base in blue.

It's using 31.6 mA from 1.25 volts and working into two tiny 20 mAh 3.7 volt batteries for the shots, charges them well too.
..
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Vortex1 on June 11, 2014, 08:38:22 PM
It is fairly straightforward to calculate the operating characteristics of the circuit, considering the current gain in each transistor, then the maximum npn collector current can be known and this will be the point where the  inductor ramp current switches state.

I have been trying a number of things to avoid current wasteful "hard turn on" of the pair.

I have used a variable resistor in the collector base connection which seems to work.

Another method is to turn the pnp into a limiting current source. With drive limited to 1 mA at the base of the npn, and considering a gain of 100, then 100 mA will be the switchpoint for inductor current.

The simplest is to just limit the base drive current to the pnp by a suitable resistor in series with the pot, but then the resistor in series with the cap becomes the peak current adjustment limit.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: TinselKoala on June 12, 2014, 02:06:12 AM
I know this one doesn't meet the criteria, but when I look at Sucahyo's circuit I just have to respond somehow.


Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 12, 2014, 03:31:06 PM
Yeah, again can you give any description of what we're seeing there ? I'm sure if I was using a transistor with a rating of 100 volts I could also light up an NE-2.  :) My intentions are to harvest low voltage energy sources that are unusable for much else and boost the voltage so that over time the energy can be stored and used from batteries or used intermittently like a flasher light.

The above circuit with less than ideal parts can run the battery down to 0.8 volts and it's still pulling 3.5 mA and boosting the voltage to 2.9 volts in a 25 Farad capacitor. When the cap is at about 3 volts ( can go to 5 volts ) it will then run the CMOS LED driver circuit for some time using the previously stored energy and the 4 x 5 mm LED's will be bright enough for a night light. I actually need a night light now because my goats are kidding and I need to get up during the night to check they're ok.

The circuit I posted I will be transforming, I hope by using an inverter gate in place of the pnp transistor and using MPSA18 NPN transistor for the main switch. Then by applying a high signal to the inverter gate input it's output should stay low and turn off the first stage according to a sensed voltage or such arrangement. CMOS is good because it has low power consumption. Gates can be paralleled to increase output power and they can drive transistors directly (with some help for some).

The CMOS LED driver circuit could be more efficient as well, and run from about 3 to 5 volts. It could also boost the 3 to 5 volts from the first circuit to up to 15 to 20 volts to dump into a 12 volt lead acid battery to rejuvenate/desulfate/charge a small one or similar.

I've ordered some 2N7000 mosfets and some Schottkys. As well I might look into a sub 3.3 volt micro controller, to control the initial and secondary circuits.

..

Some shots as the supply voltage drops.

..

Title: Re: Single Coil Two Transistor Boost Circuits
Post by: MarkE on June 13, 2014, 07:06:45 AM
Is D1 helpful in that position?  With it in the circuit as is, Q2 and Q1 will only turn off very slowly.  I also recommend changing D2 to a 1N5817.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 13, 2014, 11:13:16 AM
That works well Mark, Thanks very much and thanks for taking the time and effort to modify the drawing, much appreciated.
The circuit seems to be now taking about 200 nS to turn off if what I'm looking at is correct. Now is there a better way to adjust the conduction time of the transistor ? It's ok how it is, but there must be a better way. With your modification it now can go to a minimum off 20 uS and uses about 38 mA from 1.3 volts at 38 kHz, but it can be adjusted down to about 9.7 kHz and then it uses 111 mA with a 80 uS on time, Maybe 80 us is a bit long for that coil, not sure. Anyway it now adjusts a bit different I'll run it till the battery get down again and see how it goes.

Vortex did mention putting the diode there as well.

I might need to PM Stephan and get him to edit the first post for me edit time is over. I can't change the bad drawing.

Mark do you think that one of those 74AUC logic gates could be used in the place of the PNP 2N2907 ? And that way keep a neat and low part count "feedback oscillator".

Below is the wave forms now, the first is the two base wave forms NPN in yellow and PNP in blue.

Second is the collector of the NPN and the base of the PNP.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: MarkE on June 13, 2014, 11:49:51 AM
You're welcome.  The 74AUC1G04 should do much better than the PN2907, particularly in being able to turn the MPSA18 off quickly.  The whole thing is a combination relaxation and blocking oscillator of sorts and depends a lot on the transistor betas and the saturation characteristics of the coil.  It is going to turn off at the earlier of C2 depleting, or L1 current building up to the point that Q1 lets go.  If that happens as a result of L1 saturation, then you've got a blocking oscillator.  If it happens because of C2/Q2/R1/Q1 then it's a relaxation oscillator.  Changing the value of C2 and R1 will change the timing in the former case.  I think that the POT R2 is kind of a dammit all.

If I were inclined to build a circuit like this to run from 1.2V, I would just pick up an NCP1400 with the output voltage I want.  Those oscillate at 200kHz, operate the inductor discontinuously, and once started with 0.9V or so will work down to about 0.3V.  It's much more of a challenge to make something work well using discrete parts, which I suppose is what's fun about these endeavors.

If you go with the logic gate, you might really want to try one of the low threshold voltage FETs that I have recommended, such as the DMG1012.  The gate charge is only about 1nC.  So if you switch around 50kHz that's only 50uA going into the drive.

As I have mentioned before, you can make further improvements with the choice of Schottky diode.  For leaded parts the 1N5817 is about as good as you will do for this kind of low power circuit.  In surface mount there are much better parts.

Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 13, 2014, 01:13:02 PM
I want it to start from about 1.1 volts but work down to or at 0.6 to 0.7 volts or so, to drain old 1.5 volt alkaline cells. I could run an oscillator like in your drawing above from a plant pot cell even. The good thing about using a single winding coil is it can be a better coil.

Thanks.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: MarkE on June 13, 2014, 01:34:10 PM
Oh, then you will want to add a bootstrap section.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: TinselKoala on June 13, 2014, 01:43:48 PM
Unfortunately the 2n7000 mini-mosfet has too high a Rdss value and too high gate threshold voltage to be much fun in this circuit. I use them frequently for other purposes but I've never been able to get satisfactory performance from JT/boost oscillator circuits operating at low voltages using 2n7000.  They make excellent LED ring oscillators though, and I use them in inverter-splitter stages for my old TinselKoil 2.0 494-based SSTC driver.

Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 13, 2014, 02:16:20 PM
Those NCP1400ASN45T1 parts are definitely on the list for next order, I can use one of those immediately. And some of those DMG1012 mosfets as well.

Tinsel, I hear ya, I got the MPSA18's for this circuit because I see you guys use them and looked up the data sheet and it looked good. I got the 2N7000's for the secondary circuit which runs from the first one.

The idea is the VLV (Very Low Voltage) circuit runs from a depleted 1.5 volt cell and boosts the voltage to about 3 to 5 volts, so then a second circuit can boost the voltage further, to maybe 10 to 15 volts. Then it can dump energy from the charged capacitor to a suitable battery using another mosfet or store it at a higher voltage till night so as to run a string of LED's better.

I could use a low power micro for the second circuit. But.... This is fun, oddly fixating. Learning a lot as well.

The second circuit I have now is a CD4049 oscillator and a MPSA06 NPN with the variable "ringy" coil you commented on, it can run from a 25 Farad capacitor initially charged to 5.3 volts and I run it down to 2.5 volts, it power's 4 x 5 mm LED's with 10.75 volts across them And 1.1 mA of current for about 4 hours. It's useful as a light for sure. Just shining directly upwards it's bright enough for me to see to get up in the night and not too bright to bother me.

I plan to upgrade that second stage as well to use the 2N7000 instead of the NPN, And maybe use a different CMOS chip for the oscillator. 

The VLV circuit is to get the 5 volts onto or "into" the 25 Farad capacitor.  ;)

..
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 13, 2014, 02:53:56 PM
Can someone tell me if this circuit "First drawing" looks like it would work ? So if there is a problem I can edit the drawing.

Second drawing has a drawing mistake as well (the capacitor C8 is upside down "might blow up like that", I'm better to draw with a pencil).
It's the circuit I use to drive the LED's from the capacitor.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: MarkE on June 13, 2014, 03:59:19 PM
With the exception that you need to protect the logic gate in both direcctions, and R9 should be much larger than the largest value of R2, the #1  circuit should work.  However it is not going to run down below about 0.9V.  I would use a BAT54S (they come in variations:  C, S, A) to protect the logic gate.  The base drive for Q1 is a power hog.  This is why I recommended a low threshold voltage MOSFET.  There are even lower threshold devices than the DMG1012 that have good specs.

If you want something that will run down to low input voltages, see my earlier post with the boot strap circuit.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 14, 2014, 01:22:18 AM
OK Gotcha, When the parts arrive I will try the basic RC oscillator (which might be the better option) and the feedback setup a few ways and see what happens.

When the supply voltage gets very low the circuit should go into "burst" mode, where the circuit working draws down the battery voltage till the oscillations stop, then the battery voltage rebuilds and the oscillations happen in bursts that give the same amplitude output voltage of the continuous oscillations (or very close to it) so the bursting oscillator will still charge a capacitor to a higher voltage it'll just take longer.

I have a Galvanic cell with a JT powered by it that lights 2 x 5 mm LED's in bright bursts at about 2 to 12 Hz of 60 kHz oscillations, the supply voltage is less than 0.5 volts RMS by my DMM. It lights the LED's bright but they "blink" so I called it "Blinky Bill"  ;D.

I intend to use that JT to flash at some plants powered by the "pot cell" while at the same time putting current through the soil for electro-horticulture experiments. That setup has been running for weeks now still with the initial wetting of the soil (no more water added yet) still moist, blinking is getting faster it seems. Likely better contact for conduction (less electrode to soil resistance).

Low DC resistance to inductance in a coil is just as important as low resistance switches ect.

..

P.S. Here's a block diagram of what I envision. I already have a less than properly efficient stage 1 - 2 and 3,... 4 can be done by simply adjusting the output of the VLV boost circuit and 5 can be done the same way but an appropriate capacitor dump/current surging charging circuit might be better suited to irregular input/output.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 14, 2014, 03:07:52 AM
I mainly wanted this thread as a discussion for alternatives to the two winding coil Joule Thief system. So any circuit that can oscillate a single winding coil "like a Joule Thief" or better then it's relevant.  :)

I set up a simple air core Bifilar coil and connected it by one of the windings bottom to the ground and the top of the same winding to a capacitance insulated from the ground, then I connected a variable 40 to 1400 pF capacitor across the other winding to tune it in and then I connected one side of the "tank" to the ground as well and the voltage became much more and the local radio signal looks quite good. See scope shot below. I tuned it roughly to the local 840 kHz - A.M. station.

I would bet that I can use a crystal radio type circuit to rectify that and maybe double it so that a cap can be charged to 0.8 volts or so. 

If not it looks good for a simple crystal setup for one frequency.

Also below is a picture of the coil and arrangement when I took the scope shot, that was BEFORE I connected the tank coil to the receiver coil and doubled the voltage and even before using a top capacitance (going by the photo), so I think one diode voltage drop could still almost double the 1 volt PP. Maybe.

I better set it back up again and check it to the drawing before I post how I connected it, my desktop computer is not fixed yet so I can't use the video camera because no fire wire on the laptop. (I'm lazy like that)
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Vortex1 on June 14, 2014, 03:39:32 PM
I suggested the diode on the base of the pnp to protect it if you are using a large value C where appreciable current could take out the base junction.

If you are shooting for high frequency operation, the diode capacitance could be a problem, it all depends on what you are trying to design.

As I said, what I posted is the elementary circuit. It was for a variable intensity led flashlight.
I'm used to designing for high volume, lowest cost of components, and best overall performance.

Imagine you had to design a variable flashlight circuit that would sell in the millions of pieces for $1 , and cost of components had to stay under 25 cents.

Where cost is no object there are numerous options.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 15, 2014, 01:15:30 AM
Hi Vortex, I did mention that you already mentioned about the diode at the PNP base, In a single line statement so you would see it.
I remember. Thanks.

For curiosity sake I ran the circuit down to 0.75 volts last night, but was unable to get it to charge a capacitor to over 3.8 volts at under 0.9 volts input, But three volts no problem.

I'm interested in building prototypes for collecting energy from as many sources for low power devices or for charging their batteries.

One use I just thought of is a light that flashes and can run from the 0.5 volts of a regular pot galvanic cell. I've made one already it is just a joule thief flashing 2 x 5 mm LED's 24/7. I sealed it up in a plastic box to make it waterproof with just the LED ends poking out like eye's, then I glued a light tube over the LED's to keep the light "directed" at the plant. So rather than just shorting out the Pot battery to get current through the soil, I can get light flashing on the plant as well as current through the soil.

Finding the best flashing frequency or frequency of the oscillations in the bursts which light the LED's might require some research.

Anyway, to run from a Pot cell the oscillator needs to have a very small current draw or be able to work in burst mode.

One situation where as much current as I can get is best.

I get current through the soil output and I get light output and I think the plants will benefit from the oscillator near it. Time will tell.

There are a multitude of uses for these type of circuits and extreme efficiency is not always required, especially if the input is free scavenged energy or energy otherwise not usable. Any circuit that works will work. Logically.

..

P.S. As Pirate said and the electro-negativity scale shows that a carbon magnesium battery works best for what we can get a hold of easily. Part of an old Mag wheel for the more negative element and a carbon arc gouging electrode or other form of carbon
for the less negative element. If no Carbon or magnesium then zinc/galvanized steel and copper.

..
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 15, 2014, 04:12:00 AM
The circuit with the PNP and NPN Bipolar transistors shows the below wave form at 0.76 volts input while working into a 25 Farad supercap. With the MPSA18 transistor a better PNP or a single logic gate (which is a bunch of mosfets working as one switch) and Shottky's  , I bet it could go much lower for a small expense in parts.

..
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: TinselKoala on June 15, 2014, 07:51:44 AM
 8)

Title: Re: Single Coil Two Transistor Boost Circuits
Post by: magpwr on June 15, 2014, 09:50:47 AM
8)

hi Tinselkoala,

I do admire your work.You do emphasize on "well crafted base" for certain experiments which 18th or 19th century scientist or engineer would do in order to present their invention to the world in a more
appealing approach.Nothing beats the classic way of project presentation.

Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Dave45 on June 15, 2014, 01:28:37 PM
8)
Now thats interesting,
and all this time I thought you were just a follower  ;)
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: TinselKoala on June 15, 2014, 05:13:58 PM
Now thats interesting,
and all this time I thought you were just a follower  ;)

I see that you aren't familiar with my YT channel.

I neither lead nor follow. I sweep up the candy wrappers and cigarette butts and half-eaten cheese sandwiches that are tossed away by the aficionados following the blind tourguides through the maze of the OC. (overunity catacombs)
While the "fish" are stumbling over the boulders, tripping into streams and bumping their heads on the ever-lowering ceilings on their fantasy tour, I take the bits and pieces they discard, ignore and fail to recognize, and I make beautiful and functional, or at least operational, things with them.
Along the way I try to leave signposts warning of dead ends and blind alleys, but people still ignore the signage and get lost in them anyway. You can hear their pitiful moans and groans and lost scrabbling scrapings, if you listen closely.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 16, 2014, 08:30:50 AM
Tinsel, Crystal radio ? I guess FM Band ? Nice setup, does it have the jumper for the LED or radio selection ?

If I had a better function generator I would go for a mHz radio because there is more power there I think, some of the mHz stations just south of here are a lot higher power than the one AM station just north of here, when i say just north it's 30 klm and south is about the same or a bit more.

Can you explain the arrangement for me please, it is relevant due to being an emergency source of light and radio messages of a safety nature.

All low voltage sources of power around that we can use will apply to these circuits, thanks for posting. Safety is always relevant.

Cheers
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: TinselKoala on June 16, 2014, 05:15:37 PM
Tinsel, Crystal radio ? I guess FM Band ? Nice setup, does it have the jumper for the LED or radio selection ?
Yes, crystal receiver. No, not FM, just ordinary AM standard broadcast band. I do have a couple of designs for FM broadcast crystal sets but they are something else entirely, requiring careful construction because of the high frequencies.
The LED is just permanently in circuit, in parallel with the output. Many crystal radio circuits put a resistor and capacitor filter across the output. I didn't see any effect of that on this unit so I left it off, and the LED will often light up even when the audio output is also in use.
Quote

If I had a better function generator I would go for a mHz radio because there is more power there I think, some of the mHz stations just south of here are a lot higher power than the one AM station just north of here, when i say just north it's 30 klm and south is about the same or a bit more.
More power in the transmission perhaps, but harder to deal with using "garage technology" because of the high frequencies. Also more subject to line-of-sight transmission paths. You don't get much "skip" at FM broadcast frequencies, but sometimes you can pick up strong AM standard broadcast stations for thousands of miles.
Quote
Can you explain the arrangement for me please, it is relevant due to being an emergency source of light and radio messages of a safety nature.

All low voltage sources of power around that we can use will apply to these circuits, thanks for posting. Safety is always relevant.

Cheers
Sure, I didn't mean to hijack your thread, but as you say it's relevant, and illustrates several important principles, like sympathetic resonance and the use of natural materials, and of course the "variometer coil" tuning trick. This is kind of a single-coil that allows one to flip over half of it without disconnecting. I think a properly built one could smoothly transition between fully "bifilar" behaviour (very small inductance) to full monfilar multilayer air-core behaviour with relatively large inductance. This one goes from about 100 uH to about 160 uH ( or at least it did before I took a few turns off for tuning to 1200 kHz. A little lower figures now.)

I plan on building a tunable coil like this for JT use. It will need some more wire than this one, though, since it's air core, to reach the needed inductances for JT behaviour, I think.

I got the basic idea for the setup from the Heart of England crystal radio club, which in turn posted an article from Popular Wireless magazine from 1925 detailing the coil construction. Look at these beautiful builds of ancient designs:
http://crystalradioclub.co.uk/g4wpw.htm

Here's a video I just uploaded, demonstrating the "Australia" Variometer Galena Crystal Radio.
http://www.youtube.com/watch?v=cBEhtzGcYW4

I hope I don't get flagged for "copyright violation" since there is some AM broadcast music heard. YT actually flagged me for some motor noise in an earlier video, even "identifying" the specific source, some weird CD of electronic music. But I had no music, just motor noise! So I disputed it and a few days later the flag was removed. Some human at YT probably got a bit of chuckle out of that.

Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 16, 2014, 10:14:25 PM
Yeah you tube tried that on me too but I disputed it as well and had the flag lifted, they do it so they can force advertisements on people. They threatened me with legal action and yet there was no copyright infringement, they should be prosecuted for harassment. Basically if your neighbor plays loud music and you make a video they foist copyright infringement action on you, but it's ok by them as long as you allow them to place free ads on the video. If the copyright was actually the point to it they would just demand it be removed period. I would argue in court it has nothing to do with copyright and only to do with forcing ads on people, even on those who capture content that cannot be heard by the human ear, as well as anything the "machine" thinks might sound like copyrighted content. Once you make a successful dispute they should leave you be as they know they are wrong legally. It's all bluff.

Having said all that if we do place a video with a radio station playing, as long as we mention the music is courtesy of the radio station "Mention Name" and they are the ones playing the music, then we should be fine as we are not claiming anything is "our" content.

I think once they get a dispute over a copyright infringement where they are clearly wrong that they remove your channel from the scans. For fear they will be prosecuted for false copyright infringement claims or harassment, if they make several false copyright infringement claims on the same person then they can be prosecuted for harassment because that is what it is.

I urge all to dispute any BS copyright claims made by you tube "on the behalf of artists", because that is not why they do it.

Anyway, I see you use an antenna, I just use a Tesla coil as the antenna and a ground connection (isn't that what a Tesla coil is anyway a "Transceiver", I can listen to the radio with a Tesla coil tuned to 833 kHz, no need for an outside antenna. I think there is a practical advantage to that in that I can get radio to listen to without  even going outside. I can use piezoelectric ear buds or by using a very small amplifier that runs from a AAA battery.

I can also "locally" block a band out of the middle of the tuning range for the 833 broadcast on a hand held regular radio by tuning in the Tesla coil under power in continuous wave mode. It makes a real neat totally silent space in the middle of the tuning range, hilarious.  :)

Cheers


P.S I was using the Tesla coil one day with solid state switching, " just out of tune and making plasma streams" and the "noise" could be heard several kilometers away on a car radio, the person was on the way to my home and as he got closer the noise got more then he said as he drove up the driveway it stopped, that's because I turned it off when I seen him coming so I could go talk to him. hahahahha
..

Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 16, 2014, 10:47:06 PM
I got some of the ordered parts from one place and so I was able to put some 1N5819 diodes in the prototype, I also changed the variable 800 uH - 3.3 mH coil from the secondary circuit to the VLV two transistor circuit which lowered the frequency to a range between 3 and 13 kHz and now the wave form looks much better on that circuit. On the secondary circuit I changed to a 37 uH coil and using 2.5 uS I can get the power output I want at only 45 to 60 kHz even though the circuit can work up to 800 kHz as it is.

Out of curiosity I set up another three gate oscillator on the other vacant side of the CD4049 and I got it to oscillate at 1 mHz no problem and fairly stable with only 3.5 volts input, I think on a board it would work even better, It needs at least 50 pF timing cap to be stable. If I just put a 100K resistor across one gate it oscillates at 4 mHz but the signal is curvy.  :) A "odd number gate" ring oscillator is easy as well.

The CMOS cookbook says this CD4049 chip can make a good several mHz oscillator, it also shows a circuit for a square wave generator from a few Hz up to HF. Very handy book.

..

P.S I think if I want to use a logic chip as a second stage oscillator (3 to 5 volt) and use some of the gates for "control" turning off and on other parts of the set up, then I should use a Schmitt trigger chip or regular CMOS chip (not a CD4049), then I can use a rising and falling divided voltage to trigger a gate to change it's output. Maybe. Logic chip = 25 cents but a picaxe 08M2 = 3 or 4 dollars.

..
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 20, 2014, 09:53:07 AM
Wow does SMD stand for "Super Minute Devices" or "surface mount devices", these things look like fleas stuck to a piece of tape.
I'll need to sharpen my soldering iron point, find some tweezers and solder some pins on one of each part to prototype with. Or maybe I can make some tiny adapters with little bits of circuit board. I've got PCB making gear to make a simple tiny board.
My oh my so tiny.  :) Will make a compact circuit though.

..

Title: Re: Single Coil Two Transistor Boost Circuits
Post by: TinselKoala on June 20, 2014, 11:08:47 AM
I can think of some other things it stands for!

Here is some inspiration:

http://www.youtube.com/watch?v=-KMLmpC7-Ls
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 20, 2014, 02:38:26 PM
hahahaha I must have ordered the smallest package available.  :-[ yesterday I made the slowest resonant charging circuit I ever did
and today I soldered the smallest electrical component I've ever even seen I think.

Check it out, it's not even 2 mm x 1 mm ....  umm..."big".  ;D I just hope I didn't fry it with the solder, the first one I lost on the floor,
I had it about to solder the first pin and turned to grab the soldering iron then when I looked back it was gone, I was holding empty tweezers.  :o  ::)

Anyway as long as it's not fried I got one to proto with, this is a 74AUC. Do they come in a slightly bigger size at all ?

Next a diode, easy peasy.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: TinselKoala on June 20, 2014, 05:10:25 PM
There is an easier way....

http://www.ebay.com/itm/like/280817219646?lpid=82

Make yourself some of these with copper-clad PC board material. You don't even need to etch, you can remove the necessary copper using a thin-bladed saw kerf. Tin the pads with solder first. Then the devices are pretty easy to handle, you just place them on the pads, hold down with tweezers, then drag the soldering iron across the pads to melt the device leads in place. With appropriate flux, there won't be any solder bridges where they shouldn't be.



Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 20, 2014, 07:50:15 PM
Yeah I'll sort something like that out later, thanks for the heads up, when I'm ready with a working prototype circuit I'll make a board.

As far as the logic gate oscillator goes, it doesn't for some reason, with power connected the output went high and stayed high, I was using an almost dead battery though 0.8 volts. So I set up the feed back oscillator and it is working ok with an MPSA18 bjt.

With the MPSA06 transistor it used a lot more power and drew the battery down to 0.708 v so I changed to the MPSA18 and after about an hour the voltage hasn't fallen below 0.74 volts and the LED seems just as bright. Will be good when I use a mosfet and sort out a better oscillator, might need two gates for a regular type logic oscillator.

But it only works so far with the diode back in the stingo position. Also using diodes to protect the gate from going too negative.
I didn't put the neat little output Schottky in there yet, just bunged an LED in it, The little Schottky reads only 0.08 volts forward voltage with my meter.

first shot is the logic gate input and output.

second shot is the logic gate output and the collector.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: mscoffman on June 21, 2014, 03:37:36 AM

Your crystal radio post brought back a lot of memories from when I was a kid. We had a powerful local radio station several miles
away that would pretty much swamp everything else. But we could get it to play through a speaker directly. We also had a
150' outdoor long wire antenna. I guess that's were I got started in free energy. We used to keep a neon bulb across the ant.
When the bulb began flashing it meant that a summer thunderstorm was near-by.

BTW Got any of those New Zealand amplifying crystals?

:S:MarkSCoffman
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 22, 2014, 04:37:29 AM
I cant get the single gate astable oscillator to work, single gate works with feed back but power draw is a lot more, but a two gate astable oscillator works a treat, just like any other Logic gate oscillator, fast and sharp wave form, and these run down at very low voltages. I get very similar wave forms now as with the higher voltage CD4049 oscillator. Now is just a matter of finding a compromise between the highest voltage running condition and the lowest voltage running condition. eg. the right inductance and frequency/on time to work ok through the entire range. I think I'll copy the inductance and frequency values used by the NCP1400 (got some of them on the way as well), still waiting on the SMD mosfets. I've got some small inductors on a printer control board, I might find an appropriate one on a board. Time to pile dig.  ;D the two gate oscillator only requires two gates a capacitor and a resistor. And runs real well.

I cannot measure the input to just the two gates in operation, must be a very small draw when not driving a transistor or anything.

..

..
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Pirate88179 on June 22, 2014, 08:53:14 PM
Wow does SMD stand for "Super Minute Devices" or "surface mount devices", these things look like fleas stuck to a piece of tape.
I'll need to sharpen my soldering iron point, find some tweezers and solder some pins on one of each part to prototype with. Or maybe I can make some tiny adapters with little bits of circuit board. I've got PCB making gear to make a simple tiny board.
My oh my so tiny.  :) Will make a compact circuit though.

..

I can only solder SMD chips (surface mount devices) using my glasses, and magnifying lens (illuminated) and my Hako super sharp soldering tip.  I have no idea how you heat sink these devices to protect them.  So far, I have not fried any of them but, it is a wonder.  Some of these things I can not see with my bare eyes.  Makes for a compact circuit though.

Bill
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 22, 2014, 09:41:54 PM
The only small inductors I coud find right off are about 15 mm high and 10 mm diameter, they measure 1 mH. So I adjusted the circuit to work at a reasonable period for that coil. I have the "on time" screwed back because I'm charging two 3.6v NiMH batteries with one AAA for the supply which started at 1.38 volts so I could see how it runs with a higher input than 1.2 or under and working into a bit of load. I am using an MPSA06 transistor as I still haven't got the mosfet. The resistor R1 can be 20 to 50K, 20K is the setting to get the "on time" in the shot, but it can be more or less of course, on time can be adjustable.

I've got the batteries being charged across the 10 uF output capacitor naturally.

The frequency and width in the shot mean nothing because of the oscillations ect. It's about 46 kHz and around 8 uS on and 13.5 uS off.

Little inductor rings real good, I got two of those from an old PC power supply, less than 1 Ohm resistance.

..

Title: Re: Single Coil Two Transistor Boost Circuits
Post by: MarkE on June 22, 2014, 10:07:09 PM
The inductor ring-out is due to discontinuous conduction and parasitic capacitance.  For the most part it is neither here nor there.  It should be fun to see how low you can get the circuit to run.  The dirty trick that you might wish to try is to use a pair of Schottky diodes and a 0.1uF capacitor to form a bootstrap supply for your logic gate.  The Schottky cathodes would be common to your logic gate Vcc.  One anode goes to your battery, the other your output.  The capacitor goes from the cathodes / IC Vcc to ground.  You will have to be careful about exceeding the IC maximum voltage.  An LM4040 has a pretty small minimum current and would work to regulate the output.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 22, 2014, 10:40:09 PM
I've got BAT54C's on the way, in the bag with the mosfets. I think they are the correct one for that bootstrapping. The BAT54S's would be handy as well for protecting the logic gate output of a "drain feedback setup" maybe.

It does seem to be remarkably efficient already and it's on the solderless board with wire everywhere, on a 1 inch square PCB it should be spot on. If it will fit with the output connector and the AAA won't fit on 1 x 1 inch either, oh well. It's capable of a reasonable output with 1.3 volts input and more on time.

..
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: MarkE on June 23, 2014, 01:18:40 AM
I've got BAT54C's on the way, in the bag with the mosfets. I think they are the correct one for that bootstrapping. The BAT54S's would be handy as well for protecting the logic gate output of a "drain feedback setup" maybe.

It does seem to be remarkably efficient already and it's on the solderless board with wire everywhere, on a 1 inch square PCB it should be spot on. If it will fit with the output connector and the AAA won't fit on 1 x 1 inch either, oh well. It's capable of a reasonable output with 1.3 volts input and more on time.

..
Great.  I am glad you are having fun with the project.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 23, 2014, 05:25:03 AM
Mark, I didn't notice the "bootstrap" drawing you made at first but seen it the next day or maybe two later. With 1.4 volts max input voltage it should be ok. I'll test the lowest voltage the circuit will run to with the mosfet for the switch and no bootstrapping first, then I'll try it with the bootstrapping. I notice with the bjt when the input voltage goes below 0.7 volts the collector voltage begins to rise before tun off. And the output becomes very small. Maybe the mosfet will stay on better.

I think with the bootstrapping the circuit would run to produce a constant output from a single galvanic cell, enough to boost voltage into a 50 Farad cap or small rechargeable battery, which can then be used to dive several LED's at good brightness for some time with a non bootstrapped circuit. Many ways to utilize over 1.5 volts.

The regular CD4000 series chip will work from three volts ( a bit less ).

Thanks for the help.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 23, 2014, 07:28:28 AM
The dirty trick that you might wish to try is to use a pair of Schottky diodes and a 0.1uF capacitor to form a bootstrap supply for your logic gate.  The Schottky cathodes would be common to your logic gate Vcc.  One anode goes to your battery, the other your output.  The capacitor goes from the cathodes / IC Vcc to ground.  You will have to be careful about exceeding the IC maximum voltage.  An LM4040 has a pretty small minimum current and would work to regulate the output.

Would it be possible to use one of those LM404's to turn off the oscillator when the desired voltage is reached ? Connect the cathode to the output and the anode to a logic gate input ? Maybe with an additional resistor or two.

..
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: MarkE on June 23, 2014, 03:11:06 PM
Would it be possible to use one of those LM404's to turn off the oscillator when the desired voltage is reached ? Connect the cathode to the output and the anode to a logic gate input ? Maybe with an additional resistor or two.

..
Yes, you can use it to kill the oscillations instead of just loading the source.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 25, 2014, 03:38:47 AM
OK, I think this PCB design will work for a basic fixed frequency and fixed pulse width unit, I got confused a bit because the SMD
parts I'm using on the solderless board for prototyping are upside down and when I use both SMD and through hole components
I'll need to either solder the through hole parts up off the board, or put the SMD parts on the copper side and the through hole parts
on the other side. Should be ok, I think I'll do that to keep all the parts right down on the board. I could solder some through hole
parts like SMD parts such as the resistors, but I'll see how it looks.

The board should measure 45 mm x 22 mm. The connectors won't need to jut out, and I might modify the PCB design to include
2 x 5 mm LED's permanently between the diode output and the positive rail so there is always some load. Then when the output
between the circuit ground and diode output is loaded the LED's will go out if the load takes enough power to drop the output to
below the LED conduction voltage. I know loading the ground to diode output down to 4 volts puts out the LED's.

Just a basic design to test efficiency. I still need to nail down the exact timing capacitance and resistors, looks like 200 pF will be
enough timing capacitance so I'll work it out from there. On the solderless board there is loads of parasitic capacitance so the PCB
device will operate a bit different.

Anyone see a problem with the traces ? Logic gates at bottom, timing resistors above, timing cap to the right of those, inductor to
the right of that, and mosfet just below with the output diode near the output capacitor.

The board needs one jumper from the timing capacitor to the timing resistors and logic gates junction point.

..

P.S. I can add the loading LED's by simply soldering them to the spare bit of copper near the output diode and the positive rail,
I can drill holes if I want them solid mounted on the PCB or I can use wire and mount them in the case shining out.

And the circuit is also attached. With the optional LED's shown between the output and + rail.  I think it's all drawn correctly.
The circuit is working fine but I cannot rule out drawing mistakes. so I ask for checkers, please. Ileft out the timing resistor values
because they will depend on the inductor and the users wants.  The timing cap can be whatever is applicable to a persons needs
as well. I'll use a 1 mH inductor so I'll want about 50 to 80 kHz with about 30 to 40% duty, or probably about 5 uS "on" and about
7 or 8 uS "off". about.

..
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: TinselKoala on June 25, 2014, 09:12:08 AM
Looks pretty good to me so far.


Meanwhile I'm fooling around with Arduino. Here is a basic "barebones" pulser that gets to 50 kHz with a reasonable rectangular output pulse.



/*-------------------------------------------------------/     
   TK's Barebones pulser

  Enter # of microseconds for pulse to be HI in "dwell"
  Enter # of microseconds for pulse to be LO in "gap"
  +5 V pulse comes out Digital Pin 6 (or whichever you like)
  Check frequency and duty cycle on oscilloscope
 
/--------------------------------------------------------*/

#define OutPin 6

int dwell = 5, gap = 5; // Gives about 50 kHz, 50 percent HI

void setup() {
  pinMode(OutPin, OUTPUT);
}

void loop() {
  digitalWrite(OutPin,HIGH);
  delayMicroseconds(dwell);
  digitalWrite(OutPin,LOW);
  delayMicroseconds(gap);
}

Title: Re: Single Coil Two Transistor Boost Circuits
Post by: TinselKoala on June 25, 2014, 04:21:27 PM
It takes a little time to turn the Arduino output on and off, so at very short intervals the actual pulse you get is longer than the "delayMicroseconds" would imply. This is why you need to check with a scope and fine-tune to your exact requirements by "fudging" the dwell and gap values until your actual output is what you want.

For example, here's what you get with gap = dwell = 2 "microseconds".


Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 26, 2014, 01:05:42 AM
Tinsel doesn't the Arduino software have a "pwm wizard" to calculate and produce the required code for specific frequency and duty
cycle for pwm capable outputs ?

Seems like one advantage of the picaxe is that it can run from 5.5 volts down to 3 volts. And pwm outputs only require that two fields be entered into the pwm wizard, the frequency and the duty, it then gives the code to paste into the program.

The pwm output never exactly matches what we want unless all the timings add up neatly. That is the one thing, but it does get very close.

..
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: MarkE on June 26, 2014, 01:18:49 AM
It takes a little time to turn the Arduino output on and off, so at very short intervals the actual pulse you get is longer than the "delayMicroseconds" would imply. This is why you need to check with a scope and fine-tune to your exact requirements by "fudging" the dwell and gap values until your actual output is what you want.

For example, here's what you get with gap = dwell = 2 "microseconds".
This assembly code  can be called using the following prototype with values from 1 to 256 (pass in 0) and will generate a delay of 8N ticks including the basic call and return overhead.  If you need a very specific absolute and short delay of M clocks, then you can insert in-line assembly of RJMPs and NOPs.  RJMPs take two clocks and NOPs one clock.  Or you can code RJMPs in C:

goto mylabel01 ;
mylabel01:
goto mylabel02 ;
mylabel02:
...
goto mylabelx ;
mylabelx:


The overhead may be higher in Arduino land.  It takes a grand total of 12 bytes instruction memory.

void delay8NTicks( unsigned char n ) ;

//----------------------------------------------------------------------------------------------------------------------------------
// delay8NTicks
//
.nocc_start
_delay8NTicksLoop:
    rjmp   _delay8NTicks01 ;
_delay8NTicks01:
    rjmp   _delay8NTicks ;
_delay8NTicks::
    dec    R16 ;
    tst     R16 ;
    brne    _delay8NTicksLoop ;
    ret ;
.nocc_end
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: TinselKoala on June 26, 2014, 01:34:05 AM
Tinsel doesn't the Arduino software have a "pwm wizard" to calculate and produce the required code for specific frequency and duty
cycle for pwm capable outputs ?

Seems like one advantage of the picaxe is that it can run from 5.5 volts down to 3 volts. And pwm outputs only require that two fields be entered into the pwm wizard, the frequency and the duty, it then gives the code to paste into the program.

The pwm output never exactly matches what we want unless all the timings add up neatly. That is the one thing, but it does get very close.

..
No, the Arduino handles PWM differently, I think. It produces either the "fast PWM" at 62.5 kHz or "phase correct PWM" at 31.25 kHz and provides 256 levels of duty cycle from 0 to 100 percent at those frequencies, on all 6 of the PWM-enabled pins. "analogWrite(pin, value);"  is all that's needed to set the PWM output in code. The actual PWM frequency can be "hacked" by more complex coding to produce other frequencies but this is waay beyond where I'm at.

The sketch above seems to be the most flexible way of doing pulse control with full frequency control up to 80 kHz and duty cycle from 1 to 99 percent. I've written a more complicated program that uses two potentiometers to set the "gap" and "dwell" parameters live while running, and displays the values on the LCD screen, but I won't bore you with that.

This is interesting though. Here is another way of doing the same thing, but restricted to 50-50 duty cycle. But it's slower! Can only reach about 68 kHz. with "1" set as pulse duration, whereas the first sketch gets to 80 kHz with both dwell and gap set to "1".

// TK's Barebones Pulser 0
// Symmetrical (50-50 duty cycle) 5 V pulses on OutPin

int OutPin = 6;
int Vout = LOW;
int pulse = 1;  // sets square pulse duration (approx microseconds)

void setup() {
  pinMode(OutPin, OUTPUT);
 }

void loop() {
  digitalWrite(OutPin, Vout);
  delayMicroseconds(pulse);
  Vout = !Vout;
}

// this way gives only 68 kHz max !

ETA: Adding the line
pulse = analogRead(A1);
in the loop allows setting the frequency from between about 400 Hz to about 4 kHz by using a 50K pot, wiper to A1 and legs to GND and +5V.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: TinselKoala on June 26, 2014, 01:38:54 AM
This assembly code  can be called using the following prototype with values from 1 to 256 (pass in 0) and will generate a delay of 8N ticks including the basic call and return overhead.  If you need a very specific absolute and short delay of M clocks, then you can insert in-line assembly of RJMPs and NOPs.  RJMPs take two clocks and NOPs one clock.  Or you can code RJMPs in C:

goto mylabel01 ;
mylabel01:
goto mylabel02 ;
mylabel02:
...
goto mylabelx ;
mylabelx:


The overhead may be higher in Arduino land.  It takes a grand total of 12 bytes instruction memory.

void delay8NTicks( unsigned char n ) ;

//----------------------------------------------------------------------------------------------------------------------------------
// delay8NTicks
//
.nocc_start
_delay8NTicksLoop:
    rjmp   _delay8NTicks01 ;
_delay8NTicks01:
    rjmp   _delay8NTicks ;
_delay8NTicks::
    dec    R16 ;
    tst     R16 ;
    brne    _delay8NTicksLoop ;
    ret ;
.nocc_end

Thanks... but that's a bit over my pay grade, I'm afraid. Stirs up some deeply buried memories of long nights, cold pizza and warm Pepsi, coding nightmares better left buried and forgotten. I'll stick to my freshman Fortran-style flow that I can translate into pseudo-c++ for the Arduino IDE, and leave the Real Programming to the Real Programmers!

 ;)
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: MarkE on June 26, 2014, 01:49:02 AM
Thanks... but that's a bit over my pay grade, I'm afraid. Stirs up some deeply buried memories of long nights, cold pizza and warm Pepsi, coding nightmares better left buried and forgotten. I'll stick to my freshman Fortran-style flow that I can translate into pseudo-c++ for the Arduino IDE, and leave the Real Programming to the Real Programmers!

 ;)
The Arduino language supports the Goto statement.  You should try something like:

DigitalWrite( pinX, high )  ;
goto delay01 ;
delay01:
goto delay02 ;
delay02:
DigitalWrite( pinX, low ) ;

This should give you a four clock long high pulse on pinX.  On a chip running 8 MHz just duplicate to delay08 and you will get a 16 clock long, IE 2us long high pulse.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: TinselKoala on June 26, 2014, 04:15:28 AM
OK, that I can understand. Here's the code fully "arduinoized" and tested, runs a nice square pulse with minimal jitter at 104.8 kHz.

//------------------------------------------
//----MarkE's Pulser Code               
//----gives 104.8 kHz
//------------------------------------------

void setup(){
  pinMode(6,OUTPUT);
}
void loop() {
delay00:
  digitalWrite( 6, HIGH )  ;
  goto delay01 ;
delay01:
  goto delay02 ;
delay02:
  digitalWrite( 6, LOW ) ;
  goto delay05 ;
delay05:
  goto delay00 ;
}

//-----------------------------------------

Thanks !

(ETA: This appears to be the fastest with this method, even if I only use a single goto:delay pair for HIGH and LOW, it still runs at 104.8 kHz.)
(ETA2: Atmel 328P)
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: TinselKoala on June 26, 2014, 04:30:43 AM
Heh... the bottle neck is clearly in the "digitalWrite" statements and the main loop. (The MarkE code never makes the main loop, it's all happening inside the goto loops.)

This code produces a nice square pulse train but only 98.3 kHz!

void setup(){
  pinMode(6,OUTPUT);
}
void loop(){
  digitalWrite(6,HIGH);
  digitalWrite(6,LOW);
}

Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 26, 2014, 04:32:56 AM
For beginners like me it might help if more code is posted.

A simple single block for pin B.4 on a picaxe 14M2 to go high for 70 mS and low for 70 mS would go
Main:
       do
       high B.4 pause 70
       low B.4 pause 70
       loop

But that might be slow and not give exactly 70 mS.

Another way is the pulsout command

Block below is from picaxe manual 2
main:
        pulsout B.1,150 ; send a 1.50ms pulse out of pin B.1
        pause 20 ; pause 20 ms
        goto main ; loop back to start

For low frequency pulsing with picaxe like I did with the capacitor pulser is very easy, I just write code blocks and after the first one or two I call each one the same with ascending numbers for multiple blocks, first one or two blocks might be "Main:" or Intro:, then Main:.  A better way than using the analogue to digital converter and voltage divider would be to use a push button to send an input pin high which would cycle the program through the different blocks, if it was written to do so.

In the program below the Sing0: code block is  virtually non functional except to ensure pin B.4 is actually low to begin with and
only remains for ease of giving function back to it.

Main:
do
setfreq m4..........................................Sets core frequency, can be 4,8,16 or 32 mHz for M2 parts.
readadc B.5,b1....................................Reads Analogue to digital converter on pin B.5 to variable b1 (Pin B.5 gets the divided v)
if b1 => 160 then goto sing3..............(Depending on the Voltage level detected at B.5 and read to variable b1 jump to
if b1 => 80 then goto sing2.................whichever block the pot setting determins).
if b1 => 60 then goto sing
if b1 < 40 then goto sing0
pause 300
loop
sing0:
Low B.4
pause 1000
goto main
sing:
pause 100
do
high B.4 pause 70
low B.4 pause 700
readadc B.5,b1
if b1 < 60 then goto main
if b1 => 80 then goto sing2
pause 100
loop
sing2:
do
high B.4 pause 70
low B.4 pause 600
readadc B.5,b1
if b1 < 80 then goto sing
if b1 => 160 then goto sing3
loop
sing3:
do
high B.4 pause 70
low B.4 pause 500
readadc B.5,b1
if b1 < 160 then goto sing2
if b1 => 200 then goto sing4
loop
sing4:
do
high B.4 pause 70
low B.4 pause 400
readadc B.5,b1
if b1 < 200 then goto sing3
if b1 => 225 then goto sing5
loop
sing5:
do
high B.4 pause 70
low B.4 pause 300
readadc B.5,b1
if b1 < 225 then goto sing4 
loop


...
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: TinselKoala on June 26, 2014, 04:44:35 AM
Everything I've posted above is a complete functioning program!
Just copypaste into the Arduino IDE, compile for your particular board, upload, connect the gate of the mosfet to the Out pin and Bob's yer Uncle!

Of course your example is a lot more feature-filled, showing how you can change between program segments using voltages read from the voltage divider. I just feed in a delay figure directly using the

pulse=analogRead(potwiperpin);
delayMicroseconds(pulse);

statements or similar.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: MarkE on June 26, 2014, 05:15:36 AM
OK, that I can understand. Here's the code fully "arduinoized" and tested, runs a nice square pulse with minimal jitter at 104.8 kHz.

//------------------------------------------
//----MarkE's Pulser Code               
//----gives 104.8 kHz
//------------------------------------------

void setup(){
  pinMode(6,OUTPUT);
}
void loop() {
delay00:
  digitalWrite( 6, HIGH )  ;
  goto delay01 ;
delay01:
  goto delay02 ;
delay02:
  digitalWrite( 6, LOW ) ;
  goto delay05 ;
delay05:
  goto delay00 ;
}

//-----------------------------------------

Thanks !

(ETA: This appears to be the fastest with this method, even if I only use a single goto:delay pair for HIGH and LOW, it still runs at 104.8 kHz.)
(ETA2: Atmel 328P)
I am glad that it helps.  I have yet to dig into how Arduino code compiles.  I was hoping that the compiler would be smart enough to reduce the goto's to the next line into RJMP +0 assembly instructions.  It looks like the compiler is inserting overhead of more than 30 instructions.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 26, 2014, 05:16:47 AM
Yeah I'm keen to use Arduino so your code helps me a lot, I might get it out and have a play with it. 100 kHz or so is plenty fast
enough for most booster situations I think. I went down to 30 kHz last night messing about and my little dog started growling at me.
After a while I realized it might be the circuit noise. I wonder what our electronic world sounds like to a dog. Probably very noisy and annoying.  :-\ One reason I think I would like to use about 60 kHz or above, surely they couldn't hear that.


P.S. I was writing my previous post before the last two went up I think. Mine looks out of place now a bit. But anyway some might use picaxe. I think micro's are a great way to control and interface separate circuits, as well as they can do a lot themselves.
..
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: TinselKoala on June 26, 2014, 05:48:52 AM
I am glad that it helps.  I have yet to dig into how Arduino code compiles.  I was hoping that the compiler would be smart enough to reduce the goto's to the next line into RJMP +0 assembly instructions.  It looks like the compiler is inserting overhead of more than 30 instructions.
I can't see any big change in frequency when I use 4 or 6 pairs of goto:label statements, and since the main loop with just the write instructions is actually slower than the goto loop, I think that the extra overhead is mostly in the write statements. I might do some additive tests to see how many goto pairs I have to put in before the frequency changes much.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 26, 2014, 11:51:36 AM
I noticed with this circuit that when the load is 3 x 5 mm LED's between the diode output and the positive rail that the ring down is clipped on
the negative side of the oscillations and the very first one seems to have a "charging" type appearance but upside down.
As shown in the first scope shot.

However in the second shot with the load of 2 x AA cells in series between the diode output and the circuit ground the oscillations are free and not clipped.

It appears that if the ring down is "very ringy" when the load is between the diode output and the positive rail some power may be returned. Possibly bringing the ring down back to supply voltage quicker (if there was enough time for that).

Just a small thing I noticed, not sure if my assumption is correct. Just sayin.  :)
..
Maybe if I connect my scope to the computer I can get better scope shots.

...
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 26, 2014, 12:05:25 PM
Tonight's experiment will be to test the run time for the circuit as adjusted shown last post from 2 x 50 Farad capacitors charged to 0.75 volts each,
which is about 14 Joules per capacitor (28 total), I'll put them in series and run from 1.5 volts down to 0.8 volts, which will be 0.4 volts
on each capacitor and about 4 Joules per capacitor (8 joules total). Leaving me with 8 Joules total from 28 Joules to begin with.
So I'll use 20 Joules, and time it. I'll run the 3 x 5 mm LED's as load.
...

EDIT:....

Results: With 20 Joules it ran for 24 minutes before going under 0.8 volts, at 1.5 volts it had 8.3 volts across the LED's and they
were quite bright, at 0.8 volts input it had 7.8 volts across the 3 x 5 mm LED's, not as bright, but still bright to look at and throwing
useful light.

Works out to I think about 0.83 Joules per minute average, and divided by 60 seconds = about  0.014 Watts power draw average I think.

And it kept running for a further 4 minutes when at 0.68 volts the lights went out.

Not bad and thats with an MPSA06 transistor. about 5 on 6 off I think at the start, 1 mH inductor.

..
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 26, 2014, 03:59:45 PM
Here's a higher resolution shot of the wave form, just need to work out how to make it display more info.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 28, 2014, 04:04:12 PM
Interesting behavior from a circuit on a hand drawn PCB made to take the little logic gates soldered to the adapter's.
The circuit worked as above post shows in normal mode, then when the input capacitor voltage dropped down to about 0.75 volts the
circuit flickered the LED's for a few seconds then they light up even brighter because the circuit was operating at well over 300 kHz in
a odd feedback kind of mode (no ring down). I made a mistake on the hand traced board that I had to fix using a jumper and
stretching my timing caps out. I made the traces so I can solder the SMD mosfet on the back as well I can solder SMD Shottky's on
the back as well if I want later, 1N5819's for now.

Now the real interesting part, it ran for about an hour from a 50 Farad capacitor charged to 1.16 volts even using the MPSA06 transistor.
I ran it down to 0.68 volts and it was still lighting the LED's pretty well but sucking the voltage down on the cap in the higher frequency mode.
Not sure if it will do that with a mosfet.
..
scope shot shows the wave form when the circuit is in the low voltage high frequency mode. I'm only lighting 2 x 5 mm LED's now instead of three.
.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: TinselKoala on June 28, 2014, 04:33:36 PM
Here's a higher resolution shot of the wave form, just need to work out how to make it display more info.

You may find this video of use:

http://www.youtube.com/watch?v=9FDmkbCbKP0 (https://www.youtube.com/watch?v=9FDmkbCbKP0)

Also, you could position your X1-X2 and Y1-Y2 cursors a bit better; at the moment they don't seem to be related to the waveform, you just have them at arbitrary locations on the screen.

I don't know what the Rigol can display in terms of "measurements" or "parameters" that it determines from the waveform itself, especially with a burst oscillator like some of our JTs. You will probably have to do an exploration, like I showed in the video, and also use the cursors in various positions once you have a stable display of an interesting feature of the waveform or pulse train.

Nice work all around though, I'm tempted to build a "twofer" myself.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 28, 2014, 05:08:57 PM
Yeah I just grabbed that picture while I had it there, the communication between the scope and the computer is flakey, so I was
sidetracked  trying to work out why, I was lucky to get that, I think it could be the cable.

I had to order a laser printer online, maybe a week I'll have more stuff to play with, time to install a new motherboard in my desktop
computer. Laptop is a bore to type on. Thanks for the tips. I've cleaned the cable connections so I'll try again. Might work better with Linux or windows 7, this laptop is XP. USB sucks with XP.

Looks like I'll get at least the same 1 hour's run time from the second 50 Farad capacitor. The LED's have about 5.4 volts across them mostly.

Works out to about 22 Joules for an hours run.
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: TinselKoala on June 28, 2014, 05:16:25 PM
Yah, the LEDs will always act as a kind of voltage regulator, you will rarely get more than the sum of the spec fwd voltages when you measure across the LED stack. But I've got oscillators like this that will work without the LED load being in place (so it's kind of like driving a really really high impedance load). In this case the voltage can go quite a bit higher. You might try putting more LEDs in series as the load and see how high the oscillator will push the voltage. I've also found that the different colors of LEDs behave quite differently. Some have a very sharp "turn on" and others, like these red superbrights I have, seem to "leak" substantial current well before they start glowing visibly, and do glow at lower voltages than blues or whites.
Try four blues in series and see if the voltage goes high enough to light them.


Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 29, 2014, 12:53:39 AM
I think the transistor is funky, it won't work with 1.25 volts but does work with 1.16 volts, weird. Anyway, when the mosfets arrive I'll do more proper testing, this big PCB is more or less a PCB prototype, I can change stuff pretty easy but much better performance and less jitter than the solderless board. I'm going to increase the frequency, reduce the on time and try a MPSA18 transistor for something to do. I'll try 18 K and 10 K for the timing resistors and the timing capacitance can be 200 pF. Should get it up over 100 kHz and keep oscillator power down, by keeping a small timing capacitance. And hopefully if a higher frequency low voltage mode occurs it will be even higher than 325 kHz but cause a bit less power draw at low voltage. It actually lit the LED's better in the high frequency low voltage mode than in the regular mode. I've got a capacitor across the diode and circuit ground so I've got more or less DC with bumps across the LED's.

..
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 29, 2014, 02:50:53 AM
ahah, with higher than 1.2 volts input a 100 Ohms base resistor is required, I think to decouple the transistor base from the logic gates... hmmmm
With a mosfet that is not an issue. The base resistor will probably reduce the rise ad fall times reducing peak voltages and also raise the lowest voltage it will run from.
Not sure I'll have to see. But at least now it will run fine with over 1.3 volts input.

I think it will light up 4 x 5 mm bright white LED's no probs with under 1 volt input. I don't have any blue or other 5 mm LED's.

..
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 29, 2014, 04:14:00 AM
PCB Layout needs a redesign, (the PCB layout in post #63 is wrong, below picture is correct). now with the correction made to the traces the
jumper needs to go right around the resistors to the other side of them, so a redesign of the basic layout is in order.
I got confused with upside down parts and stuff. Glad I tested it out with a hand drawn bigger PCB, good to get the finer points ironed out.
..
 
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 29, 2014, 01:05:36 PM
With 1 volt it lights up 4 x 5 mm LED's ok as the picture shows anyway. But at 0.8 volts it lights them up less than I would like, and
 the power draw is more as well.
..
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on June 30, 2014, 06:28:21 AM
One thing we can do with circuits that run on low voltage is use home made primary batteries and such contrivances for the power source.

I'm fairly confident I can construct a primary battery that will supply the circuit with enough power to run continuously for as long as the battery lasts,
which could be a long time depending on the size and type. I intend to try several different methods including the bi-metal coil battery.
Building a bi-metal coil battery is not as easy as it sounds so a simpler construction might be the better option for me.
I ordered some magnesium ribbon to experiment with for magnesium-carbon batteries. Going by my experiments zinc/steel-carbon
batteries I think the magnesium-carbon combination will work well enough and be simple enough to be practical.
The challenge come in making one small but with good enough output and long lasting enough to be useful.

For situations where a stationary device needs only a small continuous input or where a device needs higher powers only part of
the time a simple primary battery and circuit to boost it's output into a storage cell of a higher voltage could be useful for long term
very cheap source of power for many things, basically anything that will run from a battery.

So with that in mind I think i want a circuit to boost the initial low power cell output into a battery of 3 to 5 volts and the circuit should
 be regulated so that it stops when the output battery is charged and restarts when the output battery gets used.

This would allow me to charge up capacitor powered torches real fast and without cranking. All I need do is primary battery
maintenance every now and then.

I could use any rechargeable battery or stack of rechargeable batteries for the output battery and simply use capacitors in a couple of torches.

The grid connected commercial equivalent would be a charge station that accepts a couple of torches containing supercapacitors,
when the torch runs low just put it in the "charge station" and its charged in a few seconds or a minute or two. No need to wait for
hours for the torch battery to recharge.

..
Title: Re: Single Coil Two Transistor Boost Circuits
Post by: Farmhand on July 05, 2014, 01:02:05 AM
MarkE was right, with the little mosfet in the circuit with the logic gate oscillator the switching goes bad at about 1 volt. So to work
at under 1 volt it needs a bootstrap setup.

The printer has arrived so I can get all fixated on designing PCB's for a while. I've got NCP1400 boost chips so I can try one of those
out too.

I made a small carbon - magnesium battery and they seem to work fairly well as compared to a piece of zinc and a piece of carbon
stuck in some dirt. 1.5 volts open circuit on a cell drops to 0.8 under the load of the circuit but charges a 1.5 Farad capacitor pretty quick.
I found that the surface area of the electrodes and the spacing are big factors in the current available, the electrodes can't have too much surface area but they can be too close together with too little resistance between them for the surface area that there is.

The carbon - magnesium battery can be constructed dry then stored and activated by adding water when desired, which could be handy for some situations. eg. hiking, when weight is a concern, dry cells can be carried and water from nature can be added to make the battery active if needed. I think the carbon will last a long time and if the magnesium can be easily replaced then it's a viable source of power for light or to recharge a phone ect.

I made a very dodgy one in a pill bottle, I could have use three times as much magnesium ribbon in it. It gave good current but the
voltage dropped a lot when loaded to 0.8 volts.