A better electric hotplate (05/05/13)

My previous hotplate didn't have any frame or means of rapid cooling, which is pretty essential when using it to reflow circuit boards. So, I built a little support frame from 8mm square steel rod and mounted a fan directly underneath. The temperature is again controlled using my software-based PID controller and one of the controller's relay outputs is used to activate the cooling fan. Both the heating element and fan are switched using solid-state relays.

I don't actually have any temperature profiles to show, but I managed to get it following a standard reflow profile pretty closely, including the cooling-down period.

Check out my pick-and-place attempt to see how I populated the board shown in the photo.