A WILD IDEA

Gramps, check the small transistors by part number to be sure they are oriented correctly. Even though the outline matches, some replacement parts have different BCE connections. The's Base, Collector and Emitter. Go to Google and search for the specs on your transistors which may be a different part than the schematic or the parts list from the original design. Double check the MOSFET, too. The orientation of the Source Gate and Drain are sometimes different on different part numbers which are substitutes but not direct replacements.

Also, the design uses two diodes that have to be oriented properly. Be sure you don't have them backwards. They are back to back and limit the positive and negative spikes of the collapsing and expanding field on the coil. They feed the resistor, as I recall.

I'll take this time to warn the DIY folks that a substitute part is not necessarily a drop in replacement. You always have to verify each part's orientation.

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,38750.msg239165.html#msg239165

I was using one that is 450 uH but that one is encapsulated and I can't remember if it is shielded or not (Carl highly suggests it).  I looked around my dungeon and found an unfinshed coil that I wrapped in spiral wrap and it came out about 500 uH I then shielded it and and attached 65" of Monster 2 conductor audio cable (.0275 ohms/ft.) it now measure 550 uH @1.5 ohms, it still sends up smoke signals.  I checked the transistors and diodes as GD suggested all are correct.  Gotta take something for this damn headache, later dude.

Gramps

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,38750.msg239253.html#msg239253