Thread: Big Joule Theif
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Old 11-23-2010, 06:00 PM
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Vaporizer Vaporizer is offline
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@ Tectalabyss,
I see. That point (E-C) is normally 1 LED or neon to show the oscillator is running, nothing more. Many remove it once a stable secondary load is established to reduce primary current draw from the battery. The paralleled LEDs there are lit by the feedback signal, but are also still on the source battery side using battery current too. Most use a separate winding(pickup) on the toroid to run them. This way all they see is the voltage developed by the collapsing magnetic field of the oscillator, never actually connected to the battery side, and totally isolated.
That should help your time run. Lidmotor has a good example of that with Jennas light vid. He has a 3" toroid running a CFL. The JT is only ringing the toroid, everything else is picked up from the tertiary(3rd) winding. He has room in that vid for many more separate windings too. Its pretty impressive to watch when you think of what its doing. I'll find the link if you need me too.

Edit: Actually, the one LED/neon also protects the transistor from HV spikes till a load is used to do more than just a simple JT circuit. Needed to clarify so ppl didnt start blowing transistors!
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Last edited by Vaporizer; 11-23-2010 at 06:59 PM.
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