Recent content by jhsellers

  1. jhsellers

    Backplane PEM spring holder

    Ahh - so the iron doesn't pull the PEM out of alignment as the solder is setting. That makes sense now. Thanks, JHS
  2. jhsellers

    Backplane PEM spring holder

    For use exactly how? Sorry, but I can't picture the utility of these. PEMs have to connect to the collector/case of drivers, right? Will the spring tension do this, so that the insulator isn't crushed? Is that the proper use of the springs? Thanks, John
  3. jhsellers

    Fluke 289 v 87V

    I was in division engineering - building products manufacturing (lumber, plywood, OSB, gypsum); we did everything from power distribution down to plant control. Most of my colleagues were SMEs for process control (programmable logic controllers, distributed control systems), but my focus was...
  4. jhsellers

    Fluke 289 v 87V

    Arc flash - the meter range switch was not rated to interrupt the available fault duty on that 480VAC circuit. More electrical accidents are now attributed to arc flash (burn hazard) than they are to shock hazard. This was my career - analyzing distribution systems for available fault duty...
  5. jhsellers

    Leach amplifier?

    Nice digging, Mark. Yep, those resistors are used as fuses. Is that the protection, or is there another part of the design that acts from a fault? Thanks, I learned something from discussion with you. Best, John
  6. jhsellers

    Leach amplifier?

    Mark, Sorry, but I have no more information readily available - save what you've already studied on the GT.edu site. I only have the circuit boards from my own ambitions to someday build one of Leach's amplifier designs. Never made judicious downloads of the build notes, although I probably...
  7. jhsellers

    Leach amplifier?

    Hello, all. Wondered if anybody here has experienced the Leach amp? http://leachlegacy.ece.gatech.edu/lowtim/ The late Marshall Leach was my advisor when I was in school. He was considered an eminent authority on audio technology in his time, but I've no idea how that equates to recent...
  8. jhsellers

    Speaker hookup question

    Maybe, but then a lot of guitar players would be losers. ;)
  9. jhsellers

    Speaker hookup question

    Judicious, but not such that I want to dampen the music. Series connection will dramatically limit the audible power developed. The fact that most of us here love power amps - making half-vast assumptions - means that we love to crank it once in a while. :) JHS
  10. jhsellers

    Speaker hookup question

    Hello, all. I'm a recent newbie to this forum - lurked for some time, and finally registered since I have an original Phase Linear 400 that I bought new in 1974. Because I've not been a regular visitor, I had not seen this thread regarding speaker loading until today - seeing that it's...
Top