Heater Controller

[mosleyl98]

I built a heater for my telescope mirror using 20 1/2 watt resistors in parallel. I am using a 12 volt battery and I want to build a simple controller with a LED light to show on/off and a way to vary temperature. Any help would be appreciated.

 

[em2006]

I suggest you to use a thermostat.

 

[stevez]

Do you want to turn the heater on or off - or would you like to vary the power to the resistors??

Seems to me that there is a fan controller IC that might be easily adapted. How much power will the circuit have to handle? Is it 10 watts or something different?

 

[Hero999]

Here's a simple thermostat.

 

[Analog]

You need to measure the temperature, then compare it to a setpoint. A simple bang-bang controller could be made with a 3 terminal temperature sensor, a pot to set temperature, a comparator to compare the two values, and a power mosfet to drive the resistors. If you want to go advanced, a PWM setup can vary duty cycle etc., but I am not sure how much you want to put into this, or if tight temperature control is required.

 

[Analog]

Here's a simple thermostat.

where???????????

Okay, now I've seen you've added it.

 

[em2006]

Some ideas, to inspire you:

Desin Idea - Fan controller adapts to system:
**broken link removed**

Datasheet TDA21801:
http://www.infineon.com/upload/Docu...s/012/2955/DS_FanControl_TDA21801_Rev2.11.pdf

Therno-Fan
**broken link removed**

Thermal control:
http://www.cpemma.co.uk/thermal.html

 

[mosleyl98]

It is 10 watts. I want to turn it on and off and vary the power to the heater
Thanks

 

[Hero999]

That should be no problem, any of the idea listed above will work. With my circuit I recommend replacing the PNP transistor driving the relay with a P-channel MOSFET and using that to drive your heater.