Joule Thief

[altrez]

That's right Altrez and the high frequency changes many things in the circuit equation one of which is the amount of current you need to light a LED.

Thanks Stprue! I was pretty sure that's what was happening.

-Altrez

[sirmikey1]

  Do you guys realize that I am speaking strictly of the spikes? The 3 volt output JT will charge a 300 volt capacitor fairly quickly.   This overunity search link will show instances of "spark gap = transistor".   
   http://www.google.com/custom?hl=en&safe=active&client=pub-2734280293205008&cof=FORID%3A13%3BAH%3Aleft%3BCX%3Aoverunity%252Ecom%2520search%3BL%3Ahttp%3A%2F%2Fwww.google.com%2Fintl%2Fen%2Fimages%2Flogos%2Fcustom_search_logo_sm.gif%3BLH%3A30%3BLP%3A1%3BLC%3A%230000ff%3BVLC%3A%23663399%3BDIV%3A%23336699%3B&adkw=AELymgU2ZFBJAdG3J-iLzDCI5NFCZCjViMM4YyV6chmG-Bukhesr8W3MQ0sMHyIKYu2LwwH2wMh6452REmUJj1pJTiMG79iwqpL69RYwsT9ASQbSBlzM5i-5gSSF7TJlFm6raddjVKsZTXTaaz8PKfapkpMDEGHkgkkDDpV9zLEEnoMQ7ShPYt37i_ANneRYDGPQGQqpaLinRZi93d8TfUry_exD5-HtT9w49dlMfek0JOcMyyP-Bn6eFEB-9HVMycohYtRso7IEfB_M9U-ZugCRyMoGaZSr5-libK0lWTHsI3Xdu8GVe7Q&channel=6724390970&boostcse=0&q=spark+gap+we+now+have+the+transistor&btnG=Search&cx=partner-pub-2734280293205008%3Aw8e3l5-sj0c 

MIkey

[altrez]

  Do you guys realize that I am speaking strictly of the spikes? The 3 volt output JT will charge a 300 volt capacitor fairly quickly.   This overunity search link will show instances of "spark gap = transistor".   
   http://www.google.com/custom?hl=en&safe=active&client=pub-2734280293205008&cof=FORID%3A13%3BAH%3Aleft%3BCX%3Aoverunity%252Ecom%2520search%3BL%3Ahttp%3A%2F%2Fwww.google.com%2Fintl%2Fen%2Fimages%2Flogos%2Fcustom_search_logo_sm.gif%3BLH%3A30%3BLP%3A1%3BLC%3A%230000ff%3BVLC%3A%23663399%3BDIV%3A%23336699%3B&adkw=AELymgU2ZFBJAdG3J-iLzDCI5NFCZCjViMM4YyV6chmG-Bukhesr8W3MQ0sMHyIKYu2LwwH2wMh6452REmUJj1pJTiMG79iwqpL69RYwsT9ASQbSBlzM5i-5gSSF7TJlFm6raddjVKsZTXTaaz8PKfapkpMDEGHkgkkDDpV9zLEEnoMQ7ShPYt37i_ANneRYDGPQGQqpaLinRZi93d8TfUry_exD5-HtT9w49dlMfek0JOcMyyP-Bn6eFEB-9HVMycohYtRso7IEfB_M9U-ZugCRyMoGaZSr5-libK0lWTHsI3Xdu8GVe7Q&channel=6724390970&boostcse=0&q=spark+gap+we+now+have+the+transistor&btnG=Search&cx=partner-pub-2734280293205008%3Aw8e3l5-sj0c 

MIkey

Hey Mikey,

I guess i am a bit confused about what spikes you are referring to? The JT is a tank circuit "Ham Radio Talk" It works by using high voltage high frequency. Now i am sure there are spikes on the back end of it.

I am just having trouble understanding what you are trying to explain?

-Altrez

[MrMag]

MrMag,
  The pdf doesn't mention the spikes at all; and I had never realized that this was not well known or understood.  I have heard it mentioned here that the transistor replaces the spark gap ...
Mikey

The pdf is a pretty basic explanation of how it works. The part where they explain about the LED coming on could of been expanded a little more. Basically, the flux is built up and then when it is built up enough, the transistor shuts off and the flux is released through the LED. It's back EMF that is turning on the LED.
I wouldn't agree that the transistor replaces the spark gap. The spark gap is a completely different beast. What you are working with here in a joule thief is utilizing the BEMF to perform other work.

[sirmikey1]

Hi,
   I'm sitting here hesitant to post, thinking that maybe you guys are being humorous.  Jeanna pointed out the >300 volt spikes to me months ago. 
Mikey