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Old 05-17-2019, 03:49 PM
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citfta citfta is online now
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Hi Paul,

Well now things are looking more like a bad transistor. The voltage at the base should be stable. The fact it keeps dropping usually indicates the transistor is heating up which is what you have also confirmed. I think you have already changed the transistor once. Do you have any more you can try?

With only .2 volts on the base the transistor should not have been heating up. One thing I did notice was that your neon has a resistor in series with it. That will cause the current to be limited going through the neon. That is normally what we would want if we were using the neon as an indicator light. But in this case we want the neon to act as a safety valve to catch the spikes in case the charging batteries were accidentally disconnected. By leaving the resistor connected to the neon you may be getting spikes with enough current to damage the transistor. I would remove the resistor. You might blow the neon if you get some really big spikes but with the way your circuit is working right now I don't think you will get spikes that big.

Also when the neon is lit can you tell if only one of the electrodes inside is lighting the gas around it or are both electrodes lighting up. Only one electrode should be lit. That means the power going to the neon is DC. If both are lit then the power is AC. That may give us another clue as to what is going on.

Do you have any other electronic parts? If you have a 10k pot we could try to modify the circuit a little to see if that gets it working properly. I guess I should have cautioned you before now that a lot of what you find on the internet is not very accurate and sometimes even very misleading. Also the page you got this from claims that you can keep 4 batteries charged up while only using one to do that. I don't know of anyone that has found that to actually be true. Eventually they will all be run down. But this circuit of using pulses to charge with is very good for rejuvenating batteries that are sulphated. And getting it to work can be a great learning experience.

One other thing you can try is to insert some kind of core into the coil. It should be some kind of iron or steel. Some people have used the sleeves that come on concrete anchors and they seem to work pretty well. My coils for charging are made by winding the bifilar wire on to an empty one pound solder spool. This give me an inside core of about 1/2 inch which I fill with a bunch of pieces of electric fence wire cut to the length of the spool and packed inside the center of the spool until they are tight. Having a core and a lot more wire will give you much better charging. This may be another project for you after you get this one working properly.

I also will be rather busy over the weekend but will try to check at least a couple of times to see if you have made any new discoveries.

Take care,
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