For Sale: 3 new Watlow Digital PID temp controllers

[ken cierp]

We keep our benders well below hardwood "scorching" -- just never found a need for an elaborate temperature controller.

[Jim Ball]

Here is a pretty good outline of one way to build a digital temperature controller:

http://fretsnet.ning.com/forum/topics/d ... t%3A118289

That's nice, but a little more elaborate than really necessary. For one thing, avoid cold joints on thermocouples.. It's best to connect the thermocouple wire directly to the inputs on the back of the controller.

I scrounged a 16/3 power cord and three-prong receptacle from an old dead computer I hadn't got around to recycling yet. The switched receptacle is unnecessary, but an inline fuse is a good idea to protect everything.

A 600 watt heater is only about 5.5 amps at 110 volts. I do not think that massive heat sink on the relay is necessary. A simple piece of U-shaped aluminum channel large enough to mount the relay to will be sufficient. (don't forget the conductive paste between them.)

The separate switch for the blanket is, IMHO, an unnecessary embellishment. The controller is lit up - the blanket is on - duh!

There is absolutely nothing wrong with that controller setup in the link. It is just more than the minimum needed to do the job - and I really do not like the thermocouple setup.