Electronics > Projects, Designs, and Technical Stuff
Do sub 0.1 ohm variable resistors exist?
digsys:
Easy - pick up one of these and rewind it to whatever range / value / current you want. If it needs constant adjustment, get one with a wiper arm. Done it in the past.
Gyro:
Assuming that this is a one-off application... You can still find good old fashioned cylindrical rheostats at low resistance and high current. Eg. https://www.ebay.co.uk/itm/Tubular-Resistor-Rheostat-10A-5-Ohm-5P-60-A348367-61-RAF-Vintage-Aircraft-Spare/323713607813?hash=item4b5ed5a885:g:A-8AAOSwqKFdE2RA
I have a 3R3 one at 10A (330W) that I use as a variable load. You won't find as low as sub 0.1R but you could use a higher value one in parallel with one or more low value fixed shunt resistors to do fine adjustment.
Jeroen3:
I have used an 1 Ohm 50 Watt rheostat. It doesn't have many steps though... It's wound with ribbon instead of wire.
This one I think.
If you're looking for sub 1 Ohm rheostats, you're probably doing it wrong though.
I specifically needed for a test scenario to vary the load on a digital current source. Sometimes they are also used as correction for current transformer in generators. Funny stuff they've invented before the age of semiconductors.
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