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Author Topic: Single Coil Two Transistor Boost Circuits  (Read 56348 times)

Farmhand

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Re: Single Coil Two Transistor Boost Circuits
« Reply #30 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.

TinselKoala

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Re: Single Coil Two Transistor Boost Circuits
« Reply #31 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.




Farmhand

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Re: Single Coil Two Transistor Boost Circuits
« Reply #32 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.

mscoffman

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Re: Single Coil Two Transistor Boost Circuits
« Reply #33 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

Farmhand

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Re: Single Coil Two Transistor Boost Circuits
« Reply #34 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.

..

..

Pirate88179

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Re: Single Coil Two Transistor Boost Circuits
« Reply #35 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

Farmhand

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Re: Single Coil Two Transistor Boost Circuits
« Reply #36 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.

..


MarkE

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Re: Single Coil Two Transistor Boost Circuits
« Reply #37 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.

Farmhand

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Re: Single Coil Two Transistor Boost Circuits
« Reply #38 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.

..

MarkE

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Re: Single Coil Two Transistor Boost Circuits
« Reply #39 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.

Farmhand

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Re: Single Coil Two Transistor Boost Circuits
« Reply #40 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.

Farmhand

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Re: Single Coil Two Transistor Boost Circuits
« Reply #41 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.

..

MarkE

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Re: Single Coil Two Transistor Boost Circuits
« Reply #42 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.

Farmhand

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Re: Single Coil Two Transistor Boost Circuits
« Reply #43 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.

..
« Last Edit: June 25, 2014, 07:52:06 AM by Farmhand »

TinselKoala

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Re: Single Coil Two Transistor Boost Circuits
« Reply #44 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);
}