PWM for temp control?????

[abunaitoo]

PWM= Pulse Width Modulator.
I use it to control speed on DC brush motors.
Has anyone tried using it to control pot temp?????

[z28z34man]

They make a PID that dose PWM but a standard PID works very well and is cost effective so why put the extra strain of turning your pot on and off 60 times a second to use PWM

[edctexas]

Essentially a PID box senses lead temp with a thermocouple probe and regulates the AC applied to the pot. PWM does not really work on AC. It is normally used with DC to regulate the amount of power. The PID box normally uses an SSR or mechanical relay to switch the AC on and off. The relay switching is more coarse and not being synchronized with AC variation can wear out its contacts. THe SSR or solid state relay switches when the AC voltage is low and when the AC current is zero. It does need some sort of metal object attached to it to release its heat. Some PID units actually can control the AC to 1/2 cycle although most cheaper units do not. You could use a light switch dimmer to have variable power, but there is no temperature feedback. The PID, by using a thermocouple, does two things for you. It measures the temperature and uses that to control the power to the pot. It maintains +/- 2 to 5 degrees except for when you throw scrap or ingots into the pot. You don't actually "need" a PID. It is an aid to more precision in boolit casting. You can cast plenty of good boolits with just a thermometer.

Ed C