3v OU Flashlight

[verpies]

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]

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]

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]

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.

[stivep]

https://www.youtube.com/watch?v=1BNgo09N0yM


Wesley