In Reply to: One-Shot Pulse (about 5 min length) posted by Teddy on 10/19/01 at 1:24 PM:
If you need timing intervals measured in anything from multiple minutes to longer, I'd really suggest doing it digitally. If you count the 60 Hz line frequency for five minutes, the total count would be 60 x 60 x 5 = 18000 counts. This isn't so bad. A 14-bit counter goes up to 16384 while a 15-bit goes to 32768.
Trying to make long duration timers with analog circuits is a painful business. It always was, but years ago when unijunction and complementary unijunction transistors (General Electric's D5K1 for example) were in vogue, there really wasn't much choice.
John Dunn - President