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Old March 16, 2017, 03:24 PM   #178
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Join Date: June 8, 2016
Location: Cleveland, Ohio Suburbs
Posts: 1,451
I'm always surprised, given the need to supply power to these simple oscillators abruptly enough to ring the tank circuit, that folks still use mechanical relays for it. Cheap high current P-channel MOSFETs can be had to do the job and electronic timers with high speed TTL compatible outputs are a dime a dozen. The schematic topography would be something like:
While I agree with you 100% the use of relays and contactors does not really surprise me. My experience with these annealing units is that the guys making them are not for the most part engineering types but rather electronic hobby enthusiast. Logic Level gated MOSFETS are a great solution and have the fast turn on times required. While they can be connected in crude fashion to really incorporate them you need a board and heat sink.

While neither is difficult they make a relay with screw or lug terminals, like an automotive relay lucrative. Anyway, this would be my best guess as to why relays and contactors lead in the popularity roll. Pure speculation on my part. Heck, I would also consider the use of some uC units. Figure you can buy uC chips pretty inexpensive and they are not that difficult to program for timing functions. While I have never really played around with them a Rasberry Pi can be had for less than about $35 and could likely run all the control functions for an annealer. I really don't know.


Last edited by Reloadron; March 16, 2017 at 03:33 PM.
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