I'm new in this site And sorry for my english language..

I need a circuit for my little oven.

I use an incandescent bulb (4x100W) for heating, and I want make a dimmer circuit to change output using a temperature sensor (ptc or ntc).

I have an AC Light Dimmer I want to modify. I want to change the potentiometer to ptc but I can't find a 470k ptc...

What are your ideas for it?

enter image description here

Can I use this circuit?

With PIC16F88

  • 1
    \$\begingroup\$ Show us the schematic diagram of your existing dimmer. \$\endgroup\$
    – Dave Tweed
    Mar 4, 2016 at 21:10
  • \$\begingroup\$ If you do replace the pot with a thermistor, be aware that the thermistor and related wiring is potentially live and dangerous. Is the dimmer potentiometer used as a voltage divider or just as a rheostat? \$\endgroup\$
    – jms
    Mar 4, 2016 at 21:23
  • \$\begingroup\$ How about PWM a solid state relay to turn the bulbs on and off, with the pulse width set by the error signal from your temp sensor, set point. \$\endgroup\$ Mar 4, 2016 at 21:36
  • \$\begingroup\$ @DaveTweed I have wall type dimmer I don't have schematic i63.tinypic.com/14o29hc.jpg \$\endgroup\$ Mar 4, 2016 at 21:51
  • \$\begingroup\$ @GeorgeHerold Is it problem constantly on-off for incandescent bulbs? I can use basic relay circuit with ntc or ptc... \$\endgroup\$ Mar 4, 2016 at 21:54

1 Answer 1


Here's an example citcuit for using a thermistor & PWM controller (you could hack a dc/dc converter controller to do the job) as a thermostat to run your lights. The xfmr is to drop your AC mains voltage down to whatever supply voltage your MCU needs (a wall-wart would work, as long as your GND isn't isolated).

enter image description here

  • \$\begingroup\$ Thank you a lot of dear.. What is value D1, D2, and MCU And last thing is how can I set max. temperature..? \$\endgroup\$ Mar 5, 2016 at 1:15
  • \$\begingroup\$ D1 & D2 are diodes, any diode rated to the voltage & current will work. As for setting the temperature, that depends on what MCU you choose to use. With some, a variable resistor would work well; for others, can set temperature with software. \$\endgroup\$ Mar 5, 2016 at 1:26

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