"Tim Williams" wrote in message
...
"Oppie" wrote in message
...
http://webpages.charter.net/dawill/I...odiode_PWM.gif

Geez, I haven't futzed with PUTs in ages. Does anybody still make them?

PUTs aren't that hard to find. Maybe you're thinking of UJTs?
http://www.mouser.com/ProductDetail/...URy1Y7q4hnw%3d
Although I'll admit none of them are actually *in stock* right now.

Anyway, if they're on the expensive side ($0.25 in singles?), you can
Jeorgify your own from a 2N3904 and 2N3906 ($0.06/ea in singles)... the
equivalent circuit is as indicated (i.e., like an SCR, but take the second
junction).

Tim


Last time I worked with them was about 25 years ago. It was used as a
oscillator/ramp generator for a proportional heating control system in a
'Centrifichem' blood chemistry analyzer.
Oppie