Thanks for sharing your circuit, Bob... Have you done any measurements to see how constant the temperature is maintained over time? Looks like a neat little circuit for a couple of other applications.
73, Tony W4ZT [EMAIL PROTECTED] wrote: > At 1/8/2007 15:22, you wrote: >> Hi Bob, >> I would like to get a copy of that circuit if you have one available. >> >> Thanks, > > OK, here is the circuit I used. The original National Semiconductor > circuit had a 30 K resistor in series with a 400 uF cap., both in parallel > with the 100 K resistor on the input of the 1st LM324 section. I found > that combo to actually destabilize the operation of the controller for this > particular application, so I removed them & changed the 2 uF cap in series > with the 10 megohm resistor to 5 uF. That cap is a non-polarized paper > capacitor; I believe a 4.7 uF non-polarized ceramic should work as well. > > The 1/4 watt heater resistor & LM34 temperature sensor are mounted on the > same side of the crystal but separated as far apart as possible. > > Bob NO6B
