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By way of background I was trying a short while ago to rebuild this magnetic pendulum circuit that I found in the magazine Nuts and Volts, http://nutsvolts.texterity.com/nutsv...?folio=36#pg36 . I had different transistors and a different coil and was having trouble getting it to work. I figured it was all the changes to the specs but I also at one point thought, I can't keep the pin-outs straight on transistors, and so I flipped the NPN. It still didn't work and now when the magnet came by the coil stuck to it and started humming. I felt stupid but then thought, well, that should mean the coil is oscillating, maybe Bedini has taught me something, that humming might be useful in a different scenario. So I hooked up a bridge rectifier across the coil and sure enough it was pumping out the spikes, so I went from stupid to "hey this guy's good". I first thought it would be a very particular sort of thing, but it isn't. I have run this with a PNP PN290A mated to an NPN 2n2222 or 2n4401 or 2n3904 (if memory serves). Right now I am running a Tip 42/Tip 31 set-up, it just goes. I have oscillated 10 turns or 1000 turns, straight welding rod cores and toroids, even air cores. What I am having most success with right now is toroids.
I have some toroids from Nebraska surplus with pretty high magnetic permeability I took a two inch one and put 70 winds on the primary and 900 winds on the secondary. Was getting 400+ plus volts off the secondary with a 1.5 volt input, however, after playing with it for a while I saw that for charging batteries I was getting best results off the 70 turns. So I am finding good results from just throwing 100 turns on a toroid. It seems to work a bit better than a joule thief.
The way to tune this is by changing the 1mOhm and 100K pots. For each value of the 1mOhm pot there is a best value for the 100k pot. If you open the 1 MegaOhm pot up all the way you may fry the transistors, it certainly looks to go from oscillating to wide open. If there are very few turns on the coil there is only a narrow band of resistance where the coil oscillates.
So aside from from having great fun radiantly restoring batteries and wanting to share this I am also posting because I feel a bit like Goethe's Sorcerer's Apprentice fiddling with the two potentiometers. I have no idea why this circuit works but it does so and consistently with a variety of parts. I don't have an oscilloscope and this is the first time I have really wanted one, to look at what is going on with the wave form and how it might change with changes in resistances.
I hope people replicate this circuit and if someone explains to me how it works that would be great.
ZPDM
PS There is a small chance the circuit diagram is wrong, it is the first time I have used software to diagram a circuit, I think it is right but if there are problems let me know so I can correct them.
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