mosfet matching ?
Zen Mod,
I've gone through a couple of rounds of measuring the IRF510 mosfets, and I'm not getting much variance. With a 1.1K resistor to give around 30mA, I'm measuring around 3.92v (using a Shunty as the power source), the difference between individual mosfets being only .01 or .02, so by these measurements I'm having no trouble finding 'matches'. Does this seem right? I thought there would be bigger differences (maybe because the multimeter resolution is only to 10mv?).
Tod
Zen Mod,
I've gone through a couple of rounds of measuring the IRF510 mosfets, and I'm not getting much variance. With a 1.1K resistor to give around 30mA, I'm measuring around 3.92v (using a Shunty as the power source), the difference between individual mosfets being only .01 or .02, so by these measurements I'm having no trouble finding 'matches'. Does this seem right? I thought there would be bigger differences (maybe because the multimeter resolution is only to 10mv?).
An externally hosted image should be here but it was not working when we last tested it.
(First column here is 30mA some have 2 measurements, second column is not usable info, third column is 20mA - I tried to let the temp settle on these measurements, but I was still seeing +- 10mv when I would remeasure them)
Tod
Thanks! I'm going to scrounge for those parts and hopefully give it a go tomorrow.
The Shunties are both assembled and tested, so if I can get the Pumpkins assembled I can test them this weekend
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Tod
mosfet matching w/ LM317
Got that LM317 rig setup for the N-channels, and they are all testing from 3.93 - 3.96 v, so confirmed that these mosfets are all within very close tolerances - super easy to find matches. On to the P-channels this evening!
The major holdup for me right now is deciding on the controls (input switch, volume) and chassis. My top choice now would be to go with a 2 chassis setup, and use the AMB Labs LCDuino volume and input selection system (AMB Laboratories), but this is a more complicated route than I was originally planning on. Need to get a few questions figured out then make a decision by this weekend.
Tod
Got that LM317 rig setup for the N-channels, and they are all testing from 3.93 - 3.96 v, so confirmed that these mosfets are all within very close tolerances - super easy to find matches. On to the P-channels this evening!
The major holdup for me right now is deciding on the controls (input switch, volume) and chassis. My top choice now would be to go with a 2 chassis setup, and use the AMB Labs LCDuino volume and input selection system (AMB Laboratories), but this is a more complicated route than I was originally planning on. Need to get a few questions figured out then make a decision by this weekend.
Tod
still making progress, and waiting....
Thought I'd post the last step I reached a month ago - the Pumpkins are all assembled, but untested. I should get them tested this weekend. Mainly I am waiting for the volume control/input selection to arrive - I decided on the Vicol Audio Maya when that was on a sale, so it is taking him a while to catch up on the orders. Once that arrives, I'll test it with the Pumpkins and double check the dimensions to order the chassis. Definitely going for a two chassis solution.
Thought I'd post the last step I reached a month ago - the Pumpkins are all assembled, but untested. I should get them tested this weekend. Mainly I am waiting for the volume control/input selection to arrive - I decided on the Vicol Audio Maya when that was on a sale, so it is taking him a while to catch up on the orders. Once that arrives, I'll test it with the Pumpkins and double check the dimensions to order the chassis. Definitely going for a two chassis solution.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
power supply chassis
Another step done, slowly but surely. Left to do: build umbilical cable, drill holes in main chassis rear panel, order main chassis front panel (getting that from Front Panel Express), assemble, test.
Another step done, slowly but surely. Left to do: build umbilical cable, drill holes in main chassis rear panel, order main chassis front panel (getting that from Front Panel Express), assemble, test.
An externally hosted image should be here but it was not working when we last tested it.
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