I'm having difficulty identifying these components. I salvaged them from a diy power supply enclosure from a garage sale. Each of the black leads in the image attached to female connectors on the face of the enclosure. I'm assuming they're transformers of some sort. Any clues would be appreciated.

Unknown parts


1 Answer 1


They’re adjustable power resistors.

You loosen the screw and move the ring to or fro to get the resistance that you want and then tighten the screw.

Probably a dummy load for various supply rails.

  • 5
    \$\begingroup\$ … and, be careful to not actually use them to their full rating on this board – these ceramic bodies are used because they can be get more than 300K hotter than their surroundings. That's not something you want epoxy to be exposed to. \$\endgroup\$ Jan 12, 2019 at 20:55
  • \$\begingroup\$ Could these be for current sensing? \$\endgroup\$
    – Pranav
    Jan 15, 2019 at 7:42
  • 1
    \$\begingroup\$ @Pranav Almost surely not. For current sensing you want a resistor that's very low value (so no need for such high dissipation) and stable - so the adjustable feature is inappropriate. \$\endgroup\$ Jan 15, 2019 at 13:15

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