Joule Ringer!

[hartiberlin]

Also it really all depends on how long your cables are
and how good all is soldered or only
connected via croco cables as this video from
TinselKoala shows:

http://www.youtube.com/watch?v=KWDfrzBIxoQ

So build up this circuit with the shortest wires you can have.

Regards, Stefan.

[conradelektro]

Scope shot over the lamp.

Sorry, no pulse or function generator in my house.

Let's just think for a while, and may be others replicate this circuit to see for themselves what can be done. Any odd fly back transformer will do, many transistors work (e.g. MPSA06, TIP31C).

Triggering the base with a "capacitor-resistor combination" or a "bifilar coil terminated with 1N60 diodes or a resistor" causes a low oscillation rate (which is good), short transistor on time (which is good), but also some complexities and instabilities.

Ladies and gentlemen, it is your turn now to show a real experiment and good mesurements.

Greetings, Conrad

[xee2]

@ Conrad

I do not want to interfere with what you and Stefan are doing. But measuring the voltage across a 1 ohm resistor between pin 2 and the timing capacitor would show how the current is flowing between the timing capacitor and the base coil. It should flow into the base coil to turn on the transistor and then gradually decrease until the transistor turns off and then (I think) have a reverse surge when the magnetic field collapses. Maybe the surge is forward instead of reversed. In that case the transistor would tun back on. I have never been able to investigate this myself. Or perhaps it would be better to put the resistor between the base coil and the base of the transistor. That would show what is actually going into the transistor base.

[conradelektro]

@ xee2, as requested

Case 1:  1 Ohm shunt between point 2 of trigger coil and 200pF-500K combination.

Case 2: 1 Ohm shunt between point 1 of trigger coil and base of resistor

I managed to bring the lamp into play, by connecting probe A to the lamp, but without using the ground of probe A. The Voltage on the lamp is high enough to cause a week signal never the less.

So, one sees, the lamp gets a pulse when the transistor opens. It does not matter much for the lamp (or the transformer) that the transistor opens up two times. But it seems that the pulse over the lamp is a bit widened at the right side because of this.

Greetings, Conrad

[xee2]

@ Conrad

It looks to me like the transistor is being turned on twice. Does it loo that way to you? I do not recall every seeing that in a Joule thief before. But, that may be because no one has ever made such good measurements. If you are not yet tired of taking measurements, this could be confirmed by putting the 1 ohm resistor between the collector and the collector coil. I think it would be better to measure with the probe at one end of resistor and the ground for the probe at the other end of the resistor. That way you know that other currents floating on the negative terminal of the battery are not getting mixed into the measurement. If this does not show the transistor turning on twice, then you were getting current coupled in through the ground on your measurements.

CAUTION - this may be a bad idea. The collector get large voltage spikes and they may be too high for your scope.