Tinkerer

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About Tinkerer

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  1. I've been using a Radioshack one that I picked up on their going out of business sale for $30. It's similar to a Hakko 937 and uses the same tips but a little fancier in presets and stuff. I really like it a lot, especially the nice cheap variety of tips you can get from china for next to nothing. Best part is the quick heating and ability to keep a consistent temp on the tip even when soldering some larger stuff. It doesn't really bog down unless you're desoldering a big heatsink or something. Though I guess anything compared to my old plain twenty year old iron would be a pretty big improvement.
  2. Turning an old capacitive terminal keyboard from 1978 into a modern USB keyboard with fully programmable keys. Got it working fine, but had to tear it back down for keycap polishing and a few minor tweaks. Currently reapplying dielectric lube to all the key stems. Need to finish up this project so I get back to testing Circlotron stuff.
  3. Gonna test the current limiter on the HV 900's today. Just double checking that this is the right setup. If it works, I should have at least one channel up and running today. EDIT: I'm just trying to puzzle it out. Diode direction for an N channel mosfet should be Source -> Drain, right. Then the resistor is 60 ohms to get a voltage drop of -20VDC to activate the depletion mode gate at around forty something miliAmps to give some buffer room for the device to fully close before the 50mA limit on the output boards. I know this is simple stuff, but when it's a hundred bucks in exploded parts and worse, the time to pull everything apart, test it and fix it up again, I just want to be 100%. I had one other question though. The output stage bias trimmer on the driver board. We keep that shorted since the two pots on the Output V2 control the bias current directly now? And is the extra DC offset resistor still required if feedback is run from the output board like the silk says instead of from the driver board? EDIT 2: Nevermind, I get it now. I need to swap them around. The body diode is supposed to point back the opposite way to act as a suppressor.
  4. I saw you had to send the PSU front plate back about three times. Magnificent patience all around to make everything just right. I barely had the patience to beat together my circlotron case out of a server rack and some extra parts when they mailed it with chips and scratches.
  5. That's a shit ton of tubes and transformers. Looks like a mainframe module from 1956.
  6. Gorgeous!
  7. The toroid came from some other big amp. I bought it second hand awhile back. The setup for the primaries is weird. The 220 is a fully separate winding.
  8. Got my spare parts GRLV PSU all finished up for the mini stax amps today. Wiring is a little ugly since I left the transformer leads long in case I ever want to repurpose the transformer again and left the other primary intact for 220V. Used an inline fuse because there wasn't really a good spot on the back panel that wouldn't look weird or collide with the board. The Kemet caps were nice and short enough for me to put in the case but since they're fat required adjusting some of the other bits before soldering to make sure they fit. Had some decent little heatsinks on the pass transistors originally, but even though the amp only pulls about 300-400mA, they got way too hot too quick. The bottom plate worked fantastic though and once assembled, the whole chassis spreads heat to all parts pretty well. And I just noticed in the picture that I forgot to scrub all the flux off those when I remounted them. Well, better go fix that. Hope you guys enjoy this particular combination of spare parts pile and overkill. Only cost me about $70 to put together with what I had laying around and half that was the case.
  9. Just a heads up that 7v reference and 1.07kOhm RN60 worked fined for 12V output. I powered it up and +11.98 and -12.00 dead steady on the board. Only need the +12 half for my purposes but I figured if I ever repurpose it later, it's easier to swap around a couple resistors than hunt down some transistors that might be OOP years from now.
  10. Does anybody know if the new US STAX distributor is up yet? I need a couple parts to refurbish an old Nova, and they're the cheapest for what I need.
  11. The nice thing about that case type if you look at the back is that it already has a few milimeters of isolation around the hole, unlike a TO-220. So the screw is all you need.
  12. I just used the same ones I use for all my TO-247 stuff. http://www.mouser.com/Search/ProductDetail.aspx?R=4180G
  13. Bumping this because I got my HV900 supplies all back up and running and need to make my last parts order to do some testing soon. I need to know the general voltage and current rating for the 60ish ohm resistor on the new current limiting adapter. Now that I looked at it closer, I think I get it. I didn't see the normally open part of the mosfet before. Also, if this works, I would assume the big resistors are not needed on the output boards. Though since I already have them, I'll probably install them anyway as long as I can find the sink space.
  14. Won't that need to be a 1kv'ish rated resistor though? Or were you guys thinking more of putting a couple smaller ones in series?