[geoff]

On 22/12/2020 1:49 pm, wrote:
Paul wrote:
=============

It's not clear to me that a thermistor would prevent a fuse from
blowing in a guitar amp, or any other circuit, that has a short
to ground. Because while the resistance may be high initially, while
the thermistor is cold, the resistance will go low as it heats up,
allowing the fuse to blow.

** Under a short circuit condition , NTC thermistors *explode*
like a fire cracker spreading debris all over the place.

Remember a light bulb in series with the AC line, is mainly a
trouble-shooting tool.

** Of course, a very primitive one that works only sometimes.

Tube radios and tube amps are the main use.

May SS amps will refuse to work with a lamp in series.


.... Phil


I think the point of the OP was that if a short on the input side of
things, the lamp would come on, and stay on. Nothing to do with a flash
of inrush current. A totally different cup of soup, and not really of
very much relevance to many real-life situations.

Of more relevance is my 240v lamp with 2 test probes that I use to
discharge valve-amp PSUs before diving in. Works well, until the lamp
turns out to be have a broken filament. Screwdriver in my other hand
stuck in the wall 3 metres behind me, and my forefinger was numb for
several days.

geoff