Western Electric KS-10376 Null Voltage Test Set

Somewhere along the way I picked up a Western Electric KS-10376 Null Voltage Test Set, made by Leeds & Northrup. It's basically a three-decade Kelvin-Varley Divider with a final two-decade precision potentiometer and a galvanometer, with a switching arrangement to either connect it as a potentiometer for voltage measurements or as a Wheatstone bridge with a 10,000 Ω reference resistor for resistance measurements.

IMG_0569


IMG_0573

Update: I cleaned up a photo of the schematic pasted inside of the case. It's available for download in my manuals area.

IMG_3321

Unfortunately the galvanometer coil was open; someone burned it out, I guess.

IMG_3332

So, I removed the galvanometer and rearranged the wiring a bit to add a pair of binding posts so I can use an external null meter.

IMG_3334

The internals are beautiful: low resistance L & N switches, precision resistors, and everything lacquered up to seal it against corrosion.

IMG_3336

The potentiometer is smooth as silk.

IMG_3328

Here's the L & N galvanometer. The magnet is the external horseshoe.

IMG_3329

It's supposed to have  1000 Ω coil, but it's open-circuited now. I didn't open things up any further.

IMG_3331

Here's how it looks when it's all assembled. The two thumbscrews are the electrical connections to the coil.

Anyone want to tackle fixing the galvanometer? It's yours for the postage it costs to get it to you. Update: someone took me up on the offer. He's using it to replace a missing galvanometer in a display piece.

© Steve Byan 2011-2016