On Tuesday 21 May 2013 21:17:53 Peter C. Wallace did opine: > >> Interestingly SiC BJTs seem relatively immune to secondary breakdown > >> (positive temperature coefficient of resistivity vs Si's negative) > >> This also means they parallel well. > > > > Si Carbide? I wasn't aware that anyone was using those for more than > > lab curiosity. > > > > In production AND affordable? > > Asking for both is a bit optimistic :-) > > http://www.fairchildsemi.com/products/sic-bjts/ > > has a little info on upcoming products
Correct. Very little, and prices are top secret, need to know stuff. Some things never change at Fairchild I guess. > and > > Cree has been shipping SIC MOSFETs for a while > (80 mOhm 1200V ~$30 each 160 mOhm 1200V ~$15 each) > These MOSFETS have characteristics that are simply unobtainable with Si That 80 mOhm is now $16.67 from the Cree dealers (digi-key et all) here in the states. And it looks great, till you look at the gate voltage swings it needs. -10 to +25? Who makes a driver for that? And/or/but I just got another wakeup call, I've been studying the spindle controllers available including the C41 I am going to re-use, and not a single one of them can exert the reverse relay without the PWM. So I either have to preface any active sink loads with a big honking full wave bridge, or use a resistor only lashup. Or buy a separate relay board & make a PSU for it. Why the hell do I have to be the only one on the planet that wants separate, independent, reverse controls? I just recently found, by watching the ammeter in series with my mills motor, that regardless of how much time I add in the .hal file to slow the release of the reverse signal, the PMDX-106 also shuts off the reverse relay the instant the PWM stops. I can do it ok with the hand switches, but an M5 in the gcode hammers the motor and the controller by opening the reverse relay on PWM stop, but the PMDX-106 analog out to the controller, or the controller itself, runs about 1/4 second late, so the driver is still driving the motor for several milliseconds after the relay releases, so the controller, seeing the motor is turning backwards when it thinks it should be turning fwd, hammers the motor with a full scale swing to over 1.5 amps. It stops the motor quickly, but also is thermally shocking the fuse, enough that a long job that uses that probing function will cost me a fuse. The fuse isn't "blown" but a strong glass will show the element is cracked & broken. Grrrr. Why doesn't somebody make reverse an independent operation, one that can be timed for best operation in the hal file and in the gcode? The interlocking with the PWM is a PITA. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! My views <http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml> Indifference will certainly be the downfall of mankind, but who cares? A pen in the hand of this president is far more dangerous than 200 million guns in the hands of law-abiding citizens. ------------------------------------------------------------------------------ Try New Relic Now & We'll Send You this Cool Shirt New Relic is the only SaaS-based application performance monitoring service that delivers powerful full stack analytics. Optimize and monitor your browser, app, & servers with just a few lines of code. Try New Relic and get this awesome Nerd Life shirt! http://p.sf.net/sfu/newrelic_d2d_may _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
