Lasersaber strikes again. A joule thief king ?

[conradelektro]

You can configure a standard blocking oscillator circuit to perform in a similar manner and with nearly identical waveforms by lightly coupling the base of the transistor to the second winding with about 100 to 200 pF coupling capacitance. A high value resistor is also needed to bias up the transistor.

What you get is an extremely narrow pulse of around 400uA into the LED, but the average is closer to 4uA, the apparent brightness of the LED being being equal to one being operated at a steady current of around 10 to 100 uA.

So we are talking about a duty cycle of around 1% or less.

I have simulated this and the LS circuit in LTSpice where exact measurements can be easily had.

@Vortex1: could you please publish the circuit diagram (of this standard blocking oscillator which performs in a similar manner) here. I have great problems understanding "verbal circuits".

I would like to try it for example with a standard Joule Thief or with my MAX931 circuit (shown here http://www.overunity.com/14591/lasersaber-strikes-again-a-joule-thief-king/msg402853/#msg402853 )

Because you ask about "utility": What is useful? What do we really need? May be it is just a mental exercise like playing chess. If you ask about utility for everything you do, you end up staying in bed all day, because in essence, nothing is useful. Usefulness is determined in the brain of the observer with very subjective criteria. "Objective usefulness" is a group exercise namely a convention, and also the group can be wrong.

Greetings, Conrad

[NickZ]

  The point is that there are some oscillator devices that do keep a useable amount of light on for a long long while, or possibly even longer. Also, finding the way to do this, even with only a single led bulb is a start in the right direction, as we must learn to walk before we can run.

[Vortex1]

Greetings Conrad

Tell me what inductance and ratio you would like me to simulate in each of the coils, maybe something similar to what LS is using. I already have a circuit that has a 1:1 ratio, 50 mH each, but it can be changed. See attached.

green =collector V
blue=baseV
red=LED current

[TinselKoala]

Dark Alchemist's circuit meets with my approval.

DALM, using MPSA18 or BC337-25.

[Vortex1]

Using the prior (simulation) circuit and substituting a 50 to 350 pF variable mica capacitor for the fixed 200 pf, I can tune the drive capacitance to look just like the LS circuit on the bench with a real circuit. I wound the pot core  using 15 mH each, winding on a split bobbin to minimize inter winding capacitance. The circuit then draws about 20 uA and delivers about 15 to the LED.

The aim was to prove that by  minimizing inter winding capacitance, I could simulate it external to the pot core winding capacitance and get the same waveform. So nothing special about the LS circuit, it is a current starved blocking oscillator.

TK: DALM, but what is the LM? Lamp for Miners?