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Old 09-27-2014, 02:54 AM
dragon dragon is offline
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Join Date: Jul 2009
Posts: 959
Hi Smokey, thanks for the kind words. I used 500 ohm coils also, tried many others that didn't work at all or worked poorly. One thing to point out that I don't think I've ever seen posted is the fact that the coil wires are also connected to the cores. I don't know where the close up picture of the buzzer came from but if you look closely you'll see the wire coming from the coil to the buzzer is connected to the core and coil. Once I saw that I realized they were shorting the coils through the core when the bar was attracted - once shorted it de energized the coils, you get a spike as it's pulled off the core by the magnets.

I don't remember the final capacitance of the wound cap, I could never get them perfectly matched - lots of screwing around with them - as close as I could get them to the stated capacitance. I tried aluminum, thin iron sheet and copper - the aluminum seemed to give the best results but its really hard to say because they all seemed to work to varying degrees - none of which I would consider completely successful.

Like you I've moved on to other projects but maybe someday I pull it from the shelf, dust it off and ponder what I may have missed...
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