Joule Thief

[xee2]

@ jeanna

I would like to try that again. Would you suggest a size and style cap

I use a small 10 uF capacitor.

Also, was the neon which you were able to light because of the base cap placed across the E-C of the transistor?

No. The C-E capacitor was just used to measure the peak voltage. It was not used with the neon bulb.

You got 100v across there?

Yes. I was able to get over 200 volts. But I needed a transistor with a high Vceo so that the voltage would not zap the transistor. The table I last posted was a test of the performance I was able to get by adding the base capacitor. Its purpose was to see what happened with the base capacitor. Lighting the neon was just verification that I was actually geting at least 100 volts out.

[xee2]

@ jeanna

How are you measuring frequency? Are you measuring using the two vertical line markers? If so are you making sure you are measuring from the start of one pulse to the start of the next pulse (not the end of the first pulse)? The time between pulses needs to be included when measuring frequency. Adding the base capacitor seems to increase the time between the pulses while the time it takes the transistor to turn on and off again remains about the same.

[jeanna]

The time between pulses needs to be included when measuring frequency.

Yes, this is how I am doing it.

I noticed I was cutting off a pixel a few days ago and I corrected the results since then. But these corrected results are what I have put on my last couple of tables about frequency. (I noticed that I was measuring from the same place to the same place and so not measuring that pixel at all. Now I land on one spot and then got the same spot one wave away and move forward one pixel so I am sure to include the spot. This makes the frequency a tiny bit longer.)

When I discovered what I was doing, It was at the beginning of a test a few tables ago. I retested that one to be sure there is no significant amount of mistake in these results.

Adding the base capacitor seems to increase the time between the pulses while the time it takes the transistor to turn on and off again remains about the same.

In fact that is exactly what it looked like before the number of turns reached the threshold. one wave, then a big space or line, then another wave. The waves looked the same but were separated by a longer line.

So, the slower frequency was not an even thing. ie. The slower wave was NOT evenly spread out over time.

I am glad you mentioned this. It means this part of your theory is still intact. There is just this threshold.

Do you have any ideas about what the 2.2MHz is all about? That is
1- a very big jump and
2- the way it looked was completely different from all the others.
Do you need me to attempt a drawing? I might give it a try.


thank you,

jeanna

[altrez]

Hello All,

I just wanted to give a quick update my new toroids have arrived! The big one is very high flux and low permeability. I have 4 other Big ones to test with.

I hope to have the big one in the picture wound with 6 pickup coils this weekend. I will post my results

Take Care All,

-Altrez   

[xee2]

@ jeanna

Do you need me to attempt a drawing? I might give it a try.

No drawing needed, your explanation is clear. Thanks for the offer. Right now I have no idea what is happening. Perhaps you can look at the voltage across the base resistor (which is also the voltage across the base capacitor). This should build up slowly until the transistor turns on and then drop sharply when the transistor turns off.