12V PTC Heating Element driver circuit.

[Cazzo]

**broken link removed**

Thats the Element. ^^^^

Basically i want to make a circuit that drives this element with correct voltage/current. but i also wanna be able to control it with a POT. either its called a variable power output or something, its been a while since ive done electronics, needa brush up.

So the driver circuit i want it to be able to change the temperature of the element when i turn the pot's knob. I'm sure its a simple circuit but i cant remeber the name of it etc. Think it might be a PWM but im not sure about the values for this element, 150W 12V, im pretty sure thats like 12.5A... again my electronics is a but rusty. but if it draws 12.5A max then its gonna need a mains supply and most likley a transformer, 240VAC - 12VDC

Appreciate help. cheers

 

[ronsimpson]

I think his heating element is designed to self regulate at 200C.
So you want to set the temperature to something less then 200C?

 

[Cazzo]

Ohk so that means when it gets to 200C it will regulate its power usage itself? and yea i need mainly 180C pretty precisely 200 is an ok number but i need to be able to get it a bit lower.

Thanks

 

[dr pepper]

A pwm circuit will probably work, however the heat output will be very non linear as ptc's usually are when not self regulating.
Do you want a schem for a suitable pwm circuit, I've used a tl494 chip on various occasions for this.

 

[Cazzo]

however the heat output will be very non linear as ptc's usually are when not self regulating.

What do you mean by that exactly? the heat wont stay at stable levels? beacuase the element regulates its voltage according to how hot it gets?

Yea sounds good on your schematic if you have a pic thanks

 

[dr pepper]

To make the heater self regulate well the heat output versus voltage (or pwm) is non linear, in other words 1/2 power probably isnt half heat, 1/4 power wont be 1/4 heat output etc, the output will level off at the rated temp.

Heres a link to the circuit I mentioned I've used this a few times with maybe a couple of changes:

**broken link removed**