matt schwartz
- Dec 10, 2015
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matt schwartz
- Dec 10, 2015
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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?
matt schwartz
- Dec 10, 2015
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- Dec 10, 2015
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- 4
He must have edited it, my forum email response says pF.
Ok great!
Ok great!
matt schwartz
- Dec 10, 2015
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My electronics guy finally appeared, says its a thermistor. Thanks!
more likely he meant a MOV, metal oxide varistor ( a special type of thermistor that is used for overvoltage protection)
not surprised
- Joined
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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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