oneTesla

GOt the unit running, after the following:

• HCT14 died after accidentally hitting pins 7 and 8 of the *21 driver with the meter probe at the same time, and I think took out the 7805 with it. Replaced with spare 7805 and LS14 (for now, was in the parts box, will order HCT14 from Digikey)
• HCT74 dragging pin 4 of HCT14 output high. Replaced with Ls74 (again, will order proper part)
• Initial test gave humming but no sparks. Had to switch the driver ICs to get unit working

So, unit works, but underwhelmingly. streamers are 1 inch long at max PW. My guess is that something is done in (either the drivers or the IGBTs). But, before I go tearing the unit apart, I am wondering if there is a "nominal test setup that will generate best case effects (tying a specific ground plane to something, etc.).

I am leery tearing into the unit, replacing all 4 parts, putting it back together, and having the same effect, and then finding out it's just the lack of a ground plane or something like that. I ask because I pulled out a 4' flourescent tube from the basement, and when I put the tube near the breakout, I get nice large streamers (only about 4 inches, but very wide) with the tube nicely lit. So, it does seem the power is there (the sound level also increases significantly in the process).

Jim

LS series chips will not work.

Thanks for the update. I purchased HCT replacements, and things are working well now. Unit is currently disassembled getting more coats of poly, as it was arcing a bit.

No amount of poly fixed the issue, but I did cut a round "shield" out of plexi that I silicone'd to the primary tube, and all is well. I recommend everyone do that, as it's trivial to do, and solves the problem for good, as far as I can tell.

Jim

good to hear!

So, just for clarity, why don't the LS versions work? Too slow? Not enough drive current?

it's fast enough but yes I don't think there's enough drive current