How to control a heater coil which is working on 220v AC through 0-5 v PWM output?

dear frnz

i want to design a PID room temperature controller to control heater coil to maintain a fix temperature . i have to control the heater thru PWM .m new to all these things.m using pic16f876 .main problem is how to control a heater coil which is working on 220volts ac (1000Watts) thru 0-5 volts PWM output frm pic16f876.
please help me
thnx

pic heater

To control an 220V load of a microcontroller you can consider TRIAC (SCRs) and an optocoupler .. see picture below ..
You can employ almost any optocoupler, but there is a family of optocouplers specially design to control Triacs - MOC 30XX (110/115 and 230/240 Vac) ..
"Phase controlled dimming is a method of providing AC power to a load only during certian phases of the AC cycle."
**broken link removed**

Regards,
IanP

triac control heater

You will have to do Phase Angle Control by taking the zero crossing as reference and then fire the SCR/TRIAC based on % output required. You cannot use the PWM engine inside the PICmicro.

Alternatively you can do cycle control to avoid switching noise.

A diagram of Phase Angle Control is below.

Cheers

Ravi

pwm heater coil

Hi,
The Phase Control is easy to build, but is not very good decision. Generate high range of noise, radiofrequency and impulse over power supply. Depend from your case you can use some like PWM but with low frequency. For example, you put the Diode Bridge; this will give you 100 Hz pulse. Use the SRC with commutation on zero. And you can regulate the power with change the Number of impulse to heather. For example, your PWm period is 1 s, and if you switch SRC only for one impulse, this is duty 1%, if switch for all 100 impulse this is duty 100%. The PWM frequency is a low, 1 Hz, but actually in many case this is enough, because the controlled object was inert ion. Also you must very accuracy calculate the time for PID algorithm, no need very fast algorithm, or high frequency of sample if you object is slow, for example ceramic furnace. If your process is fastest, you can use directly PWM or Phase Control. In this case, you must get some extra step, to reduce the radiation.