Lasersaber strikes again. A joule thief king ?

[scifi123]

Continued from the previous post:

Here is the LTSpice circuit, in case someone wants to check it out.
Download the two files in some directory and then remove the ".txt" at the end of their names so that you have two files named:

  Regen Energy_1.asc
  Regen Energy_1.plt

Open the first one using LTSpice and simulate it by doing Simulate->Run.

[TinselKoala]

I simulated lasersaber's schematics version 3 found here:

   http://laserhacker.com/?p=420

using LTSspice (see the attached image).

Unfortunately, it doesn't work: the oscillation dies quickly.
Also, the schematics seems wrong since the secondary of the transformer (L2 in the schematics) is connected to the rest of the circuit in one point (should be 2 points).



Can lasersaber or someone else tell me what needs to be changed to make it work ?

Did you try inverting the connection to _one_ of the coils? Coil phasing is critical in these circuits. Also, these are burst oscillator circuits, try a longer timebase and see if you get multiple bursts like the single one you have shown.

Study the Basic JT circuit: it may help. Note the coil connections, and compare the phasing to what you have in your spice sim schematic.

[scifi123]

  TinselKoala,

  Thanks for the schematics, it works.
  Unfortunately I couldn't make lasersaber's schematics work unless I change it so much that it's very close to yours (see attached picture).

  I still think that lasersaber's schematics is wrong since the secondary (L2 in the schematics) connects to the rest of the circuit in only 1 point instead of 2. That means that the voltage across the secondary has no influence on the rest of the circuit (it can create a current in the LEDs but that's all).

[TinselKoala]

Where did you get the lasersaber schematic from?
ETA: Sorry, I see it now.

Did you see my variation on that circuit? I'm looking for my schematic now....

ETA2: Here's my video demo including the schematics.
http://www.youtube.com/watch?v=yjgemF5zpeE

[scifi123]

  TinselKoala,

  I'll try your variation too. Just looking at it, it's clear that by adding another winding to the transformer, you provide a feed-back signal to the transistor, which is missing in lasertrader's schematics.
  I'm curious, did you get to make work a circuit similar to lasertrader's (using only 2 windings) ? If so, could you please post your circuit ?