[SOLVED] What is the difference between varistor and thermistor?

[RHeTTRoNiCS]

Been googling it also but need your ideas based on experience. Is the varistor always on a high-ohm (normally open), connected in parallel....and will "short" for any voltage surge? Is the thermistor always on a low-ohm (normally close), and connected in series...and will "open" for any increase i temp? Thanks a lot.

 

[barry]

A varistor is essentially an open circuit until its breakdown voltage is exceeded which point it begins its resistance drops steeply. A thermistor is more of a temperature sensitive resistor; it's not "normally closed", it's a resistor.

 

[kam1787]

You COULD think of varister as a zener diode

and

a thermistor as a resistor which is very temperature dependent

 

[barry]

You COULD think of varister as a zener diode

and

a thermistor as a resistor which is very temperature dependent

Right. That's what I was TRYING to say. :--)

 

[RHeTTRoNiCS]

thanks guys...really helping me...

 

[pipedoi]

thanks guys...really helping me...

Please tell me if i can't find any varistor to buy, can i eliminate it just to test a device ? I have a TNR 14V511K varistor that is fried.

Thank you

 

[barry]

That would depend on what the function of the varistor is, don't you think? If it's just for protection, go ahead and test your device.