Subject: Re: G05 transistor question(s) Date: Thu, 06 Jun 2002 From: Rodger Boots Uniwatt transistor availability and cost getting you down? Looking for better parts at lower cost?? Not scared off by the fact that pinout and heatsink mounting will be different??? WELL I HAVE A DEAL FOR YOU! But, seriously, here's what I did. I went to DigiKey, used their transistor selection capabilities, sorted the results by PRICE, and tried to find inexpensive replacements. First, the NPN transistor: MPS-U01, MPS-U05, MPS-U06, & MPS-U07 can all be replaced with a 2SD1264 at a cost of $.89 each, DigiKey part number is 2SD1264A-ND. Buy 10 for $7.42 or 100 for $59.33. (Too expensive? All except the MPS-U06 & MPS-U07 could be replaced with the 2SD2374 at $.77 each/ 10 for $6.45/ 100 for $51.59). But, you say, what about PNP transistors? MPS-U51, MPS-U55, MPS-U56, & MPS-U57 can all be replaced with a 2SB940 at a cost of $.97 each, DigiKey part number is 2SB940A-ND. Buy 10 for $8.06 or 100 for $64.49. (Too expensive? All except the MPS-U56 & MPS-U57 could be replaced with the 2SB1548 at $.85 each/ 10 for $7.09/ 100 for $56.75). Of course, as always, I could be completely full of it, but they look like they should work. And, of course, I have no way to test this myself. They handle over twice the power and way more current, but the pinout is different (so careful lead bending will have to happen to install them) and the old heatsinks might not fit. If the old heatsink have a mounting hole they should be able to be screwed to the new parts. Part of what I was trying to do was to keep it under $1 per part. As good a criteria as any. Somewhere I have several hundred TO-220 heat sinks, maybe a package deal could be made? (Uniwatt transistor used a modified TO-202 case with a thin extended tab that sticks out of the case. The transistor style of choice these days is the TO-220 which has a thick metal tab that is the entire back of the case. This allows the transistor to handle way more power and run cooler than the TO-202).