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Author Topic: 3v OU Flashlight  (Read 563361 times)

verpies

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Re: 3v OU Flashlight
« Reply #120 on: April 22, 2014, 01:53:35 AM »
Those are found if coils are scatterwound (meaning that the wire isn't laid down side by side).
I can hazard a guess that the coils are hand wound in a hurry.
Have a look...
BTW, these are the collector of C1815....
Can you show the signal applied to the base of this transistor?  ...or at least describe its shape, frequency and amplitude as well as the relation of its edge to these fast pulses at the collector.

verpies

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Re: 3v OU Flashlight
« Reply #121 on: April 22, 2014, 01:59:01 AM »
If a copper shield is present in the coil it would be an equivalent to, roughly, 11pf capacitance.
296kHz resonance would then be possible with a 27.019 mH coil.
This translates to some 500 turns if the pot core in the picture is used.
That does not compute.  The experimenter in that video states 25 turns for one winding and 50 turns for the second.

verpies

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Re: 3v OU Flashlight
« Reply #122 on: April 22, 2014, 02:03:19 AM »
It looks to me like a transistor is being overdriven into non-linear behaviour,
OK, nonlinear C-E characteristic would explain the non-sinusoidal shape of these pulses.
Nonetheless, the base of the transistor seems to be fed with constant current while these fast pulses are occurring.

It shouldn't surprise you to see a high frequency oscillation or ringing when you pulse an inductor with a slower square or rectangular pulse!
It doesn't, but the non-decaying envelope (even increasing) of these 90kHz pulses surprises me when I remember that the coil is pulsed with only ~10Hz.
The integer count of these pulses, as the core's gap is varied, also is strange, but can be explained with soliton reflection from the ends of a mismatched waveguide.

If your slow pulses are happening before the ringing completely decays it will look like constant HF oscillations superimposed on the slower stimulating pulses.
There is time for 10000 of these fast pulses between these slow pulses (100ms vs. 10µs), so this is not the case.

magpwr

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Re: 3v OU Flashlight
« Reply #123 on: April 22, 2014, 04:19:36 AM »
hi everyone,

I have attached screenshot of my back Emf produced by the 61 turns on 22AWG with copper shield with gap(gap align inside and outside during turning stage) on <3cm diameter pot core.This is my 1st winding attempt on small locally available pot core while waiting for 4.7cm diameter pot core.

Voltage 3.9volts(Li-ion)
current:6mA drawn for 5% duty cycle base on frequency 10hz.
Frequency applied:10hz....3khz produced same waveform as attached,no changes.Changes in waveform starts from 4.3khz onwards for my case.

The setup remains same using signal injected to base of C1815 transistor via 1k resistor.I'm also using 1000uf capacitor at emitter and (+) of my test circuit.

I got to head out.Time to work. ;D


stivep

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Re: 3v OU Flashlight
« Reply #124 on: April 22, 2014, 07:39:16 AM »


MenofFather

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Re: 3v OU Flashlight
« Reply #126 on: April 22, 2014, 12:36:44 PM »
OK, now we are getting somewhere...

As usual, the secret was rather simple.
Everyone assumed that the switch coil (collector of C1815) was a single coil. Am I right guys?
From + and colector transistor is a single coil with two cuper not shorted tapes, conected to that coil. But maybe cuper tapes is not nessary.

TinselKoala

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Re: 3v OU Flashlight
« Reply #127 on: April 22, 2014, 04:03:06 PM »
hi everyone,

I have attached screenshot of my back Emf produced by the 61 turns on 22AWG with copper shield with gap(gap align inside and outside during turning stage) on <3cm diameter pot core.This is my 1st winding attempt on small locally available pot core while waiting for 4.7cm diameter pot core.

Voltage 3.9volts(Li-ion)
current:6mA drawn for 5% duty cycle base on frequency 10hz.
Frequency applied:10hz....3khz produced same waveform as attached,no changes.Changes in waveform starts from 4.3khz onwards for my case.

The setup remains same using signal injected to base of C1815 transistor via 1k resistor.I'm also using 1000uf capacitor at emitter and (+) of my test circuit.

I got to head out.Time to work. ;D

Can you try the exact same setup but with a different transistor like 2n2222a (metal can), 2n3904,  or some other similar NPN silicon type? I'm wondering how much of this behaviour is due to overdriving the transistor rather than some strange inductor behaviour.

Also, I'm losing track of the actual circuit you are using. Can you please show the _exact specific circuit_ you used to make the scopeshot, just for me? Thanks.
(I've looked through my stash of Japanese transistors-- I have hundreds of them-- but sadly not a single 2sc1815. Have you tried a higher-voltage transistor like 2sc1514? )

I read this in the 2sc1815 data sheet just under the AbsMax rating table, so it must be important:

Quote
Note: Using continuously under heavy loads (e.g. the application of high
temperature/current/voltage and the significant change in temperature, etc.) may cause this product to
decrease in the reliability significantly even if the operating conditions (i.e. operating
temperature/current/voltage, etc.) are within the absolute maximum ratings.
Please design the appropriate reliability upon reviewing the Toshiba Semiconductor Reliability Handbook
(“Handling Precautions”/“Derating Concept and Methods”) and individual reliability data (i.e. reliability test
report and estimated failure rate, etc).


verpies

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Re: 3v OU Flashlight
« Reply #128 on: April 22, 2014, 04:16:29 PM »
I have attached screenshot of my back Emf produced by the 61 turns on 22AWG with copper shield with gap(gap align inside and outside during turning stage) on <3cm diameter pot core.This is my 1st winding attempt on small locally available pot core while waiting for 4.7cm diameter pot core.
The period between your pulses is approximately 400ns.  The Russian guy had 11µs.
Maybe with a larger core it will be longer.

What is the pk-pk voltage amplitude of the signal applied to the 1k resistor ?  Any DC offset ?

Voltage 3.9volts(Li-ion)
current:6mA drawn for 5% duty cycle base on frequency 10hz.
Frequency applied:10hz....3khz produced same waveform as attached,no changes.
The setup remains same using signal injected to base of C1815 transistor via 1k resistor.I'm also using 1000uf capacitor at emitter and (+) of my test circuit.
Like this ?
« Last Edit: April 22, 2014, 06:28:03 PM by verpies »

magpwr

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Re: 3v OU Flashlight
« Reply #129 on: April 22, 2014, 05:55:57 PM »
Can you try the exact same setup but with a different transistor like 2n2222a (metal can), 2n3904,  or some other similar NPN silicon type? I'm wondering how much of this behaviour is due to overdriving the transistor rather than some strange inductor behaviour.

Also, I'm losing track of the actual circuit you are using. Can you please show the _exact specific circuit_ you used to make the scopeshot, just for me? Thanks.
(I've looked through my stash of Japanese transistors-- I have hundreds of them-- but sadly not a single 2sc1815. Have you tried a higher-voltage transistor like 2sc1514? )

I read this in the 2sc1815 data sheet just under the AbsMax rating table, so it must be important:

hi TinselKoala,

This is the hardest part to advise,base on what if component is altered.2N2222 plastic transistor is definitely the most popular transistor for any low voltage circuit.
I can try out the available 2N2222 transistor only tomorrow and advise,its kinda late now over here.

Since i am living in Asia access to Japanese transistors is easy ,C1815 already existed around 20years ago when i first came across this transistor.


magpwr

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Re: 3v OU Flashlight
« Reply #130 on: April 22, 2014, 06:02:38 PM »
The period between your pulses is approximately 400ns.  The Russian guy had 11µs.
Maybe with a larger core it will be longer.

What is the pk-pk voltage amplitude of the signal applied to the 1k resistor ?  Any DC offset ?
Like this ?

hi verpies,


You got it that's my setup as describe. :)

The square waveform was set at 5volt vpp.

Since i merely constructed only 1/2 the circuit using 4069 using 10uf i noticed the blinking of led is slower.

Since base on known fact our human eyes can only detect up to 18hz led blinking rate.
Base on original video it looks somewhere between 10hz...15hz

In another words the capacitor value 10uf may need to be reduced to 4.7uf or 2.2uf .I have not tried checking the frequency from 4069 using 10uf yet.

The duty cycle need to be low to consume less power from battery.It's the reason why i mention the cap value needs to be 4.7uf or 2.2uf."But not tested yet to let me see waveform."

Base on my posting earlier in the day.I did not mention the waveform /vpp is also the same for duty cycle between 5%to 15% .I just played it safe for comment purpose at 5%.
The big different is input current consumption between 5%...15% .At 15% duty i think i was around 38mA.

avalon

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Re: 3v OU Flashlight
« Reply #131 on: April 22, 2014, 06:11:55 PM »
That does not compute.  The experimenter in that video states 25 turns for one winding and 50 turns for the second.

Glad you agree. However, I have checked (as you can see from the picture).
Little it may be it give us a clue. It basically means that the shield is irrelevant.

~A

avalon

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Re: 3v OU Flashlight
« Reply #132 on: April 22, 2014, 06:24:37 PM »

Can you show the signal applied to the base of this transistor?  ...or at least describe its shape, frequency and amplitude as well as the relation of its edge to these fast pulses at the collector.
Of course, though I am not sure how's that going to help.
Here it is. The second trace is the collector signal.

~A

TinselKoala

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Re: 3v OU Flashlight
« Reply #133 on: April 22, 2014, 09:02:28 PM »
Of course, though I am not sure how's that going to help.
Here it is. The second trace is the collector signal.

~A
Am I reading the scope right? 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.....

avalon

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Re: 3v OU Flashlight
« Reply #134 on: April 22, 2014, 09:17:44 PM »
Am I reading the scope right? 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.....
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