[Amps] inexpensive HV fuse
alexeban at gmail.com
Wed Jul 22 04:14:26 PDT 2009
Response time, guys!!!
Any thermally operated fuse is TOO SLOW to protect the tube.
Besides, the spring can carry many tens of Amperes before it heats up enough
You'll probably blow up diodes and tube and God only knows what else!
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Angel Vilaseca
Sent: Wednesday, July 22, 2009 9:21 AM
To: amps at contesting.com
Subject: [Amps] inexpensive HV fuse
Commercially available HV fuses are quite expensive.
I thought of using a small spring instead, like the ones in ball-point pens.
They are about one inch long and could be spread between two isolated
standoffs about 2 1/2 inches apart.
The ball-point pen springs are made with thin wire, but could easily
carry several hundred mA.
In case of a flashover current through the tube can reach tens of
Amperes. In that case the wire would melt, the spring would split and
the two halves would quickly retract, in less than a millisecond and
stay about one inch apart, so the arc would quickly extinguish.
I wonder if this would work. Has someone tried it?
Old Philips TV sets had a similar system on some power resistors. They
were soldered on two small springs. If the resistor became too hot, the
solder would melt and the springs would retract, thereby interrupting
Angel Vilaseca HB9SLV
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