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View Full Version : For those who understand a PID better than me.



Ramson222
09-29-2018, 04:26 AM
I've had this temperature control unit I made for brewing sitting around for a few years doing nothing. My question is this a type of PID than can be used for casting? Currently its plugged into a mini fridge. I rather use it for cast bullets than brewing. Its a STC 1000 and a wall outlet. Display is in C
228000

kens
09-29-2018, 06:32 AM
I googled that and found it on Amazon,
it said only reads up to 99C temp.
99C is boiling water only.

ChuckO
09-29-2018, 06:40 AM
An STC1000 is not a PID. It only closes a 10amp relay when the temperature gets to the set point. It has two relays, one closed when above the set point and the other closed when below the set point.

A PID uses some logic to predict the heating/cooling cycle and starts to turn the output off/on rapidly to hold the temperature near the set point. Most PID units use a solid state relay because of the rapid cycling and long relay life.

Ramson222
09-29-2018, 06:55 AM
Thank you. I did not realize it only went to 99c and that pids use logic to control temp.

HATCH
09-29-2018, 08:26 AM
another thing to consider is the probe.
228006

I don't think that will survive beyond 200 degrees F even if your controller would.


As far as PID controls go, you can configure a PID for on/off control or use the PID logic.
They will work either way and be more accurate then any factory (non-pid) furnace thermostat.
The difference is the gap between on/off and under/over shoot.

On on/off control its going to like your home thermostat. It will heat until it reaches set point. Then it will cut off. If the temp drops down a degree it may not come back on as it few degree (could be 10) window so its not constantly going on/off
On Logic control, the PID sends pulses when the temp is at set point or near set point.
It will learn (if you used autotune) the heating characteristics of your heating element and will adjust the pulses to keep the temp within range.
A PID set to logic and properly tuned via autotune will be very stable.

Dragonheart
09-29-2018, 11:51 AM
If you want to get a PID I would suggest looking on Amazon for a kit, which includes a PID, probe, relay and heatsink. A package can be found for about $40. I have had good luck with the Inkbird brand. Just make sure what you buy will support the temperature you need.