My father—in-law was an electrical engineer and had a great collection of audio and electronic equipment. I’m not sure what this is. Can anyone help?

It has a cable with 3 connectors on one end that would fit in the 3 ports on the front. The other end of the cable has red and black clamps that look like little jumper cables. There is a switch on the top like the one in front, but without a label. It fits into a nice wooden box.

  • \$\begingroup\$ The front panel is too generic to suggest a purpose. A photograph of the interior wiring would be much more informative. Is there a transformer inside? \$\endgroup\$
    – Dave Tweed
    Commented Feb 19, 2023 at 4:11
  • \$\begingroup\$ A picture of what's inside would help with an ID. \$\endgroup\$
    – PStechPaul
    Commented Feb 19, 2023 at 6:25
  • \$\begingroup\$ Is that a second toggle lever on the far/back side? What's the circle segment showing there? \$\endgroup\$
    – greybeard
    Commented Feb 19, 2023 at 8:15
  • \$\begingroup\$ Thanks everyone. I’m out of town this week but I’ll open it up when I get a chance and take some more pics and get your feedback. \$\endgroup\$
    – Dave C
    Commented Feb 21, 2023 at 2:13

1 Answer 1


Possibly a DIY phase sequence detector, along the lines of this sort of thing:

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Such a device is used to verify or determine the phase sequence of 3-phase power so that motors are not inadvertently run in reverse (which can damage some types of equipment).


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