Homebrew PCBs

"trevwhite74" <trevor.white100@...> writes:
> DJ Delorie, you mentioned before you did your own temperature
> controller for your laminator. Did you do anything special to
> control the temperature? Did you use any control loop or just on/off
> monitor of the temperature.

The thermocouple chip I used returns four samples per second, so I
just did a plain "less than=on/greater than=off" test, once per 0.25
seconds.  It keeps the heater within about 10F with a 10-30 second
cycle, which is fine for me.  Recall I'm sensing the heater temp, not
the roller temp.

I did put in a 60Hz sensor with appropriate timed delays to syncronize
with the zero crossings.  At the moment, I just use it to push the new
setting out, but I put it in in case I wanted to play with PID control
later.