1920s Battery Charger [Restoration]

So I realize this was from two years ago, but I just subbed and have been working my way though these. I don’t think this is just a transformer with a selenium rectifier. Selenium rectifiers we’re early metallic based semiconductor junctions that acted similar to diodes. They were used to rectify AC to DC similar to how diodes do today. However most I’ve ever seen are fairly large and consist of several stacked plates. This looks to me to be a vibratory half wave rectifier (though it could be full wave). Essentially the AC current flowing through the coil induces a magnetic field in the metal “band” that the lever sits in and as the voltage alternates it will cause the lever to pull to one side versus the other. When it hits one side it will connect the output and pass the AC wave but not connect on the “negative” half of the wave. Add some step down transformers and a capacitor and you have yourself a DC signal. Full wave is likely possible but it would have to be more clever.

Interesting...I know some of those words.

Hand Tool Rescue

RIGHT?! I tried contacting him, but no response.

Hand Tool Rescue

No, I love you.

Hand Tool Rescue

It’s an auto transformer with a good old fashioned selenium half wave rectifier. The knob adjust a bimetal that acts as a over current protection. It is not pole specific so it can be attached to the battery in any way. It’s not a true rectifier but more of a pulsed ac.

Its like the Fisher Price Walkie Talkie I had ask a kid! Great video. Sound is a little rough. Maybe I need to up my donation so you can get a new mike. ;D

I think I know of someone who might be able to explain how it works for you. Only issue is he's a bit shocking to work with (though usually, he's the one being shocked). Upside is, he's also in Canada, so shipping it to him will be cheap. :P

Stuart Young

I ❤ you HTR

Planky