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Ok this is bizarre there is an email from you which says something DIFFERENT like:
100Pf 600v
Trust me..
M.
??????????????? PF or NF?
100Pf 600v
Trust me..
M.
??????????????? PF or NF?
He must have edited it, my forum email response says pF.
Ok great!
Ok great!
My electronics guy finally appeared, says its a thermistor. Thanks!
davenn
Moderator
more likely he meant a MOV, metal oxide varistor ( a special type of thermistor that is used for overvoltage protection)
not surprised
hevans1944
Hop - AC8NS
A metal-oxide varistor (MOV) is a semiconductor device that is normally non-conducting until the voltage across it reaches a certain level and rapidly (think microseconds) turns it into a short-circuit. MOVs are designed to blow fuses, protecting electronics from transients. MOVs will self-destruct if too much energy is dissipated while they are conducting. So, I agree the picture probably shows an MOV device, possibly with a 300 V rating. Number of joules of energy it can dissipate without frying depends on the physical size.
A thermistor, OTOH, is a temperature-sensitive resistor that can have either a positive or a negative temperature coefficient of resistance, depending on construction. A positive temperature coefficient thermistor was often used in series with a de-gaussing coil wrapped around the shadow-mask end of the CRT in color CRT televisions, exhibiting low resistance initially to provide current to the coil and then increasing resistance and decreasing the de-gaussing current as it warmed up. I was never fond of this arrangement, but it did sort of work until the thermistor failed, usually by opening up. Then you either replaced it or used a manual de-gaussing coil if you moved the TV to a different location in the Earth's magnetic field. So the device in the picture could be a thermistor, depending on its circuit usage.
A thermistor, OTOH, is a temperature-sensitive resistor that can have either a positive or a negative temperature coefficient of resistance, depending on construction. A positive temperature coefficient thermistor was often used in series with a de-gaussing coil wrapped around the shadow-mask end of the CRT in color CRT televisions, exhibiting low resistance initially to provide current to the coil and then increasing resistance and decreasing the de-gaussing current as it warmed up. I was never fond of this arrangement, but it did sort of work until the thermistor failed, usually by opening up. Then you either replaced it or used a manual de-gaussing coil if you moved the TV to a different location in the Earth's magnetic field. So the device in the picture could be a thermistor, depending on its circuit usage.
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