Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

The way I get the temperature of the laminator is with a sensor clamped to the same spot on the aluminum frame as the original thermal switch - I do NOT think this reflects the "true" temp of rollers, but is a close as I can come.

My first attempt as temperature control was using a type "J" thermocouple clamped in place of the thermal switch, and I would watch the temperature as it heated up to around 400F (I had a Brother printer that required high temp), then run my PCB thru a few times to do the TT. One day I forgot, and when I came back the temp was up over 500F - maybe close to 600F? (as measured by thermocouple) - and the plastic frame holding the rollers inside had melted.... THAT is when I decided I had to get a "real" temperature controller rigged up.

I have heated to 425F several times in past with no problems.

I took the "spare" I had ordered, and wired in a homebrew temperature controller, using a AD22100 150C Sensor clamped to the aluminum frame in place of original thermal switch. I wired a solid state relay where the old thermal switch was and control via a PWM signal so as temp approaches setpoint, the heating is slowly dropped so as not to overshoot so much. With this setup it holds around ±3ºF. The temp will overshoot a 310F setpoint to about 311 or 312F, then start cooling, heat is applied slowly at 310F, temp will fall to maybe 306/307ºF before starting to rise again.

I've looked at using a PID algorithm to "tighten" up, but it works good anyway.

After melting the first laminator I had, I ordered the 3rd one for a spare, the 3rd is the one that came back as the single heat version. I had hoped it was the same except for being single heat, but looks like it's not?

Still having fun:)

Ken H>