It may be a resistor which can handle lots of power without burning out. Like a bulb or lamp which is under a vacuum. When the output power increases going through it, its resistance goes up, but can handle lots of power, because the air will not get to it and burn it up as quickly as if it was exposed to the air. Like a safeguard for a output stage to allow compression when the output stage reaches critical output level.
Nope, PTC's have no void between the glass and the thermistor body.
It's a resistor, encapsulated with glass to obtain a very low dT/dt value.
The shrink tube is placed over part of the glass to minimise exposure of the long lead, most folks do know what shrink tube is.
I've seen these glass things at stores, long time ago though, seen them in a few amplifiers too.
The drawing i posted is of a glass encapped resistor with excellent temperature stability.
Beats me what it does in an SMPS, temp sensing probably.
PS: often, these things are innert gas filled.
It's a resistor, encapsulated with glass to obtain a very low dT/dt value.
The shrink tube is placed over part of the glass to minimise exposure of the long lead, most folks do know what shrink tube is.
I've seen these glass things at stores, long time ago though, seen them in a few amplifiers too.
The drawing i posted is of a glass encapped resistor with excellent temperature stability.
Beats me what it does in an SMPS, temp sensing probably.
PS: often, these things are innert gas filled.
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