Light bulb limiter credit: cap47
The light bulb limiter
Just so the uninformed can know what this is.
It is a current (Amps, Amperes) limiting device to use when powering up a newly built tube amplifier
the first time or after extensive work on one. (like recapping)
It can save expensive parts like transformers if there is a short circuit or other wiring fault that draws
too much current.
It will flash brightly when the filter caps charge up then go down to a low glow if everything is
correct.
I like to use a 25 watt light bulb on a new amplifier because it limits the current to less than 250 ma
for less risk of damage if something is wrong.
Basically it puts the light bulb in series with the amplifiers power supply and reacts to the current
draw.
Very handy device. Credit definition: Structo
I tried to find the best available parts at a local hardware store. Couldn't get what I knew used to be
available so I substituted.
Power cord from an old PC I had got rid of (3 prong) and cut the end off I didn't need. Stripped to suit.
1 Metal square box, 1 metal cover plate stamped out for a single double receptacle, 1 double receptacle,
1 strain relief for the power cord. Also 1 plug in adapter standard bulb to standard male plug. Lastly an
incandescent bulb has to be used 60 to 100W. The new energy efficient bulbs will not work for this.
The amp needs to be plugged into the bottom
receptacle and the bulb socket plugs into the top receptacle. Take note of labeling in pictures.
The tab on the Neutral side of the receptacle has to be snapped off from the terminal middle of blue
and brown wire terminals. All connection are to the neutral side terminals. This sets up a series circuit
for the unit to work properly. No wires will be connected on the Gold side terminals. When the
bulb/socket assembly is plugged in the top and the amplifier is plugged in the bottom the circuit in
series completes.
This is a must tool for amp work! cap47/charliep