Resistor Choice

[pete5687]

Good Morning,

I am trying to find a resistor that will heat up and stabilize quickly ie within minutes. At the moment I am using an Arcoil resistor which at 10W is taking 3 hours + to get to a stable heat while well insulated.

I want to heat a copper block 50mm x 50mm x 25mm so that I can put a heatsink on the top for testing.

Any advice will be greatly appreciated.

Pete

 

[Skogsgurra]

A PTC thermistor heats until it reaches a certain temperature and then stays there. You may need a series resistor so it doesn't "lock" in a low current state. GIYF!

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[waross]

Have you considered a resistor, a sensor and a PID controller? It will stabilize much faster and may give a more accurate temperature.
If you want a steady flow of heat instead of a steady temperature, then use the PID setup and an over voltage to bring the temperature up fast, and then cut the voltage back and bypass the PID controller.
The copper block and resistor combination will have a thermal time constant which may be the factor dictating the warmup time.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[DRWeig]

Pete,

Think low-mass for your resistor. At 10W, though, it'll be hefty. The one you have is a good choice I think.

As Bill mentioned, it's when you add that copper block into the mix that the time constant gets up there.

Solution: many more watts and a good controller to avoid overshoot.

Best to you,

Goober Dave

Haven't see the forum policies? Do so now: Forum Policies

 

[pete5687]

Thank you for your input... much appreciated

 

[Skogsgurra]

No need to use a resistor and a PID controller. Just attach a power transistor to the copper block and use a combination of zener and NTC to control the gate (or base) and let transistor loss be your heat source. Add a potentiometer/rheostat for variable temperature. That keeps temperature decently constant also when ambient changes. How constant do you need to keep temperature?

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.