PCT question

[switchex]

I looking for small projects where PCT (positive Coefficient thermosistor) can be used to build low powered heaters.

Can you simply put a load on a PCT to generate heat? How can i determine the out put (heat) of a PCT?

My electronics knowledge is very limited and any information is helpful .. thank you.

 

[justDIY]

for a small heater, why not use a power resistor? then it's pretty easy to figure out the energy dissipation using ohm's law.

for anything larger, use resistance wire - same idea, ohm's law

might try searching for PTC instead of PCT ... usually the T is put before the C

 

[switchex]

Thanks for the reply .. so is the correct name PCT or PTC, or both?!


I am looking for an application where an area of about 2 to 4 sq/feet of enclosed area made from fabric can be heated using low voltage (12V max)without the danger of overheat, fire, and electrocution (there may be human contact). And I need somewhere between 70 to 80 degree of heat……. from my little research, my limited knowledge, these PCT heaters are perfect as they keep a constant temperature without the need of a thermostat or fan.

I am not sure what power resistors are, but i am guessing essentially a heating coil, right? and I don't think the same can accomplished with a resistance wire . .can it? I tried to search for low voltage heater on the net and found almost nothing!

from my requirements, would you think a resistor or coil heater would be a suitable option. Essentially I am building a small space heater, what are my options?

Thanks again for your reply.

 

[fingaz]

The correct term (I believe) is PTC Thermistor. PTC means Positive Temperature Coeficient

 

[justDIY]

A good combination would be a PTC to regulate the current based on temperature, and resistance wire to actually heat the area.

A current limited voltage source would be connected to a series circuit consisting of the PTC and resistance wire. The PTC could be wrapped in resistance wire to enhance the feedback effect. when the temperature is "cold" the ptc will allow more current to flow, heating the resistance wire and therefore your fabric.

as the fabric and resistance wire heat up, the PTC will warm-up and increase its resistance, limiting the current, and therefore the temperature of the resistance wire.

this is just an idea, thinking out loud. some math will probably be required to determine how much resistance wire is needed and what value PTC would work best.