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Author Topic: 3v OU Flashlight  (Read 563437 times)

verpies

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Re: 3v OU Flashlight
« Reply #135 on: April 22, 2014, 10:59:53 PM »
The Blue trace is the signal to the base of the 2SC1815? The channel is set to 5 V/ Div? So you are applying pulses of about 9V peak to the Base of the transistor?
But... but.....  VEBO is 5V Max.
Maybe he was measuring on the other side of the base resistor that dropped the voltage.

TinselKoala

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Re: 3v OU Flashlight
« Reply #136 on: April 22, 2014, 11:19:33 PM »
Hmm.... I don't get it either. The signal amplitude on the base is 2.4V
I have attached a couple of pictures. The first one is on the output of 74HC14AN (pin 6) and the second one is @ the base of C1815.

The power supply is 3.30 v
I have no idea how the error occurred.

~A
That makes a lot more sense. Maybe the scope probe attenuation was misset or something. Thanks for checking.... but now my theory about overdriving the transistor is out the window, I guess. Still, that collector current trace doesn't look right either.


picowatt

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Re: 3v OU Flashlight
« Reply #137 on: April 23, 2014, 12:02:40 AM »
Hmm.... I don't get it either. The signal amplitude on the base is 2.4V
I have attached a couple of pictures. The first one is on the output of 74HC14AN (pin 6) and the second one is @ the base of C1815.

The power supply is 3.30 v
I have no idea how the error occurred.

~A


Avalon,

The signal indicated by your scope at the base of your transistor looks like a square wave with a peak to peak value of 800mv or so.  It also has a DC offset of approx. 200mv above ground when the driver IC output is low.  Looking at your schematic, this is just what would be expected.

Regarding the transistor, the base-emitter junction appears to the outside world as a simple diode.  This "diode" (the base) begins to conduct at around .65volts (relative to the emitter) and will conduct a lot of current, just like a diode.  However, looking at the absolute maximum allowed base to emitter current in the data sheet TK provided, the base-emitter current must be limited so as not to exceed 50ma or the base junction can be damaged.

In the top scope trace, your driver IC is outputting a 3.2 volt or so pk-pk square wave.  The driver IC cannot pull its output all the way to ground, so you have a slight offset above ground indicated of a few hundred millivolts when the output is low.

The voltage between the base and emitter of a silicon bipolar transistor that is turned on will always be one silicon diode voltage drop, or between .6 and .8 volts, depending on how much current is being applied to the base and the temperature of the transistor.  Remember, a bipolar transistor is a current controlled device, not a voltage controlled device like a MOSFET.  The amount of current flowing thru the base-emitter junction is multiplied by the current gain of the transistor and that product of base current times the current gain determines the max current that can flow thru the collector emitter junction.

In your circuit, your driver IC puts 3.2V on the 1K resistor.  The base-emitter voltage is about .7V.  So, (3.2V-.7V)=2.5V, which is the voltage drop across the 1K resistor when the transistor is on.  2.5V/1000R equals 2.5ma of base current.

Regarding your scope.  The numbers in the first box at the lower left are the delta V cursor readout.  Your V cursors are not really set to measure anything in the screenshots you provided.  Using the cursor controls, move the lower horizontal dotted line (the Vref cursor) up to the channel one ground reference, which is the arrow at the left of the screen labeled "1".  Now move the upper V cursor to the top of the channel one square wave and your cursor readout will reflect the the actual voltage being output from your IC (upper screen) or applied to your transistor base (lower screen).

Similarly, you can use the time cursors to measure horizontal features. 

I can't make any sense of the "Vbt" readout, perhaps TK or someone else can enlighten us. 

Also, it looks like the trigger is set for a falling edge on channel one but the trigger level is set higher than the signal on channel one.

TK can be a great help with "scoposcopy" skills.

Regarding the weird collector waveforms, try disconnecting your coil and run a 1K resistor from the 3.3V rail to the transistor collector and then take a look at the collector signal with your scope.  If it remains flaky, your transistor has issues.

PW

Added:  Also, always try to align the channel ground reference markers with a major division on the graticule.  This makes it much easier to measure voltage off the screen by counting division.

stivep

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Re: 3v OU Flashlight
« Reply #138 on: April 23, 2014, 04:27:42 AM »



Wesley Translate's Akula video #16: Akula's TPU part 5



https://www.youtube.com/watch?v=Lpx1SJdXnmo&feature=youtu.be






Wesley
[size=0.85em]




MenofFather

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Re: 3v OU Flashlight
« Reply #139 on: April 23, 2014, 08:52:21 AM »
Не знаю, что было раньше, но теперь поставил новую 34063 микросхему, поставил 560 пикофарад купленый конденсатор и без второй микросхемы потребление 7 милиампер.
I now use new 34063 and put 560 picofarad capasitor and now curent consumption wihout second chip (it disconected) is 7 miliamps from 6 volts. But probarly I somewere made error.
Похоже правильно всё спаял и напряжение поднимает, вход 3 вольта, на конденсаторе 1000 мкф больше, но тот раз было 100-200 милиампер, а теперь 7-20 милиампер где-то или может я попортил и теперь микросхему и она не так работает как надо? Или может тогда было где-то ошибка в плате?..
Seems no errors, all errors i find and fix, maybe 34063 I brake.

magpwr

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Re: 3v OU Flashlight
« Reply #140 on: April 23, 2014, 12:13:08 PM »
hi TinselKoala,

I have attached scope shot of 2N2222a and ZTX857 (300volt transistor)

The duty cycle for 2N2222a would have to be reduced to 3% instead of 5% to maintain similar current consumption around 6mA.

The ZTX857 (300volt transistor )needs just 1% duty cycle to get around 316volts at around 6mA at 5% duty cycle it would be around 12mA.

Another interesting thing to note at 43Khz which is injected via transistor to primary coil of 17 turns would get me maximum voltage of 3volts at secondary 61 turns.
I have controlled the duty cycle to <20% to get 3volts at secondary at the same time to consume low current.

Since i did not get the MC34063 to test,lets assume if i were to tweak the output frequency from MC34063 at pin 1 to 43KHZ ,maybe by changing to suitable cap or adjusting voltage.
Then maybe this 3volts which would be present at 61 turns secondary would be amplified by the back emf by switching transistor."This is just my unconfirmed theory"

----------------------------------------------
Lastly base on recent Akula video lighting Led with flyback (NO PSU).If you noticed carefully there is 2 PWM I/C might be TL494 since there is 2 timing capacitor which is connected to the same pin for 2 I/C.
There 5 tuning knob.One i/c have duty cycle with frequency control and another I/C have the same thing but with additional fine tuning for frequency(Total 5 tuning).
I don't how mixing 2 frequency on 2 separate primary coil of flyback which connected to one end likely connected to positive supply can generate ou after looping back from secondary coil.

If you study 3volt ou flashlight circuit there should be 2 different frequency as well.

I have merely presented back emf around 10hz signal from I/C 4069 .(Bare in mind keep duty cycle low) .

Once i received MC34063 and larger 4.7cm diameter ferrite core i will complete the circuit.

------------------------------------
This is my latest findings using 4069 Photo and video attached.10uf capacitor unchanged in circuit with current consumption around 38mA using 3.9volt(Li-ion AA battery size)."I would need to use 3volts later on"

This is very interesting discovery i just made upon tuning 4069 to around 11.8hz..12hz suddenly there would be a bigger spike which appear and remain high as attached.The rest of the smaller ones is 20volts.

TinselKoala

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Re: 3v OU Flashlight
« Reply #141 on: April 23, 2014, 12:47:09 PM »
@magpwr:

Thanks for doing those tests. It looks like the 2n2222a is doing almost the same thing as the 2sc1815. I just woke up, haven't yet had my morning coffee. I'll be thinking about this and doing some fiddling around later today.

Thanks again... cheers!
--TK

verpies

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Re: 3v OU Flashlight
« Reply #142 on: April 23, 2014, 01:22:45 PM »
Wesley Translates Akula video #16: Akula's TPU part 5
https://www.youtube.com/watch?v=Lpx1SJdXnmo&feature=youtu.be
Thanks for your translation effort.

How are the copper foils connected to the windings?
Like this?
« Last Edit: April 23, 2014, 04:30:57 PM by verpies »

TinselKoala

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Re: 3v OU Flashlight
« Reply #143 on: April 23, 2014, 01:56:15 PM »
The data sheet for the MC34063A is very interesting.



verpies

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Re: 3v OU Flashlight
« Reply #144 on: April 23, 2014, 02:34:29 PM »
Do you find the VCE Max = 40V interesting?

Since there is 80V (sometimes 110V) across the collector-emitter junction of the MC34063's output transistor, this voltage exceeds its maximum VCE rating by over 200% and suggests that reversible avalanche breakdowns of this junction is occurring.
This reminds me of Itsu's and mine avalanche nanopulse generator.  See this video and this one..

Perhaps the observed train of pulses are several C-E avalanche breakdowns in quick succession.

P.S.
Weren't nanopulses deliberately used in the Dally contraption?
« Last Edit: April 24, 2014, 01:56:19 AM by verpies »

Hoppy

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Re: 3v OU Flashlight
« Reply #145 on: April 23, 2014, 02:38:53 PM »
Do you find the VCE Max = 40V interesting?

And the 7mA needed to get the output switch to conduct.

conico

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Re: 3v OU Flashlight
« Reply #146 on: April 23, 2014, 06:02:05 PM »
Verpies, What Mos-fet did you used? I used an IRFZ44n and it didn't work. :-\

TinselKoala

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Re: 3v OU Flashlight
« Reply #147 on: April 23, 2014, 06:30:02 PM »
Verpies, What Mos-fet did you used? I used an IRFZ44n and it didn't work. :-\

Didn't work, how? Did it not switch, did it blow from overvoltage, did it pop open and let the white smoke out.... or what?

Or did it "not work" simply by shutting off the LEDs when the power was removed? Good luck finding one that does "work" in this manner!



@Verpies, what do you see at Pin 12 of the hex inverter chip, the mosfet Gate? Can you take a scopeshot there?



ETA: What happens to my IRFZ44ns when they don't work:





avalon

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Re: 3v OU Flashlight
« Reply #148 on: April 23, 2014, 06:47:08 PM »
@PW.

Thank you for your post.
The truth is that I, practically, never use my DS203. It's a dinky little thing but I found hunting through some 4 buttons and 2 knobs tiring.
It is, however, a very convenient tool to quickly snap a signal and store it.  That was exactly what I did. I only cared about the input and didn't setup anything else.

All the best,

~A

verpies

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Re: 3v OU Flashlight
« Reply #149 on: April 23, 2014, 07:13:36 PM »
Verpies, What Mos-fet did you used? I used an IRFZ44n and it didn't work. :-\
Ask Akula.  That's his circuit - not mine.