http://www.8051projects.net/ Learn to make simple microcontroller projects, pic, 8051, avr and arm projects. download 8051 projects, tutorials, libraries, sample codes. join the microcontroller discussion forum and ask doubts regarding electronics. the best source for 8051 over internet. en-gb 2009-01-07T21:49:18-08:00 contact@nospam.com hourly 1 2000-01-01T12:00+00:00 http://www.8051projects.net/forum-t294.html 2009-01-07T21:49:18-08:00 Please check the circuit for CONTROLLING A 100W HEATER using AT89C51.its a 100 watt heater i want to controll using pwm of AT89C51 (pins T0, T1).the SCRs used are 2P4M. check out it and reply please.the circuits are attached. http://www.8051projects.net/forum-t294.html 2009-01-07T21:49:18-08:00 Ajay do u want just the switching or something else too? http://www.8051projects.net/forum-t294.html 2009-01-07T21:49:18-08:00 Arpit i wanna have just switching on & off the heater using these thyristors. http://www.8051projects.net/forum-t294.html 2009-01-07T21:49:18-08:00 Ajay u can do that with a relay will be easy.. i think...connect the heater plug to the relay. and switch using controller. that easier i think. http://www.8051projects.net/forum-t294.html 2009-01-07T21:49:18-08:00 Ritesh yes this can be done by using a single relay only ..no need to use SCR http://www.8051projects.net/forum-t294.html 2009-01-07T21:49:18-08:00 Ajay well.. i got a better idea.. you need not to switch on/off the SCR, better is.. simply control the gate voltage and the o/p voltage automatically gets controlled. and for this purpose use an optocoupler to connect the SCR. this is the easiest way..