Looking for manual: Strong Copper Oxide rectifier

[Tim Reed]

Does anyone have a manual for a Strong copper oxide rectifier? This is the one they introduced circa 1936, using the then-new copper oxide stack, to replace rectifier tubes.

A schematic is fine, too. This is just for my leisure, so don't spend a lot of time searching if you don't have anything at hand. I ran a pair of these as a kid, before I knew anything about electronics. Now that I'm retired, I'm curious to know more about what was a mystery to me back then.

If you would, please just send a scan to Brad so it can be preserved in the Warehouse section. Thanks! .

[Jim Cassedy]

Does anyone have a manual for a Strong copper oxide rectifier? This is
the one they introduced circa 1936, using the then-new copper oxide stack, to replace rectifier tubes.

One of my old RICHARDSON's Projection books, dated 1935, has this picture & circuit diagram of an
un-named copper oxide rectifier. I can't imagine there were that many differences between them back
then. In the early 1970's, I worked with one that looked just like this, which was made by Westinghouse.
I could tell the Cu₂O stacks and fan had been replaced at some point, but the coils, etc were original.

CuOx_DC1.jpg

The circuit is nothing fancy- - but notice no filtering. I do recall the output went through a couple of large
choke coils before going to the carbon arcs- - and I always assumed these were to remove residual ripple .
CuOx_DC2.jpg
The power was controlled by a 110v contactor type relay which, in that booth was wired so
that you couldn't start the rectifier unless the arc-exhaust fan was running, and, as you can
see from the circuit diagram, there was also an air-flow switch for the rectifier's internal fan.
I don't recall the thing putting out that much heat, but I guess those copper stacks would
overheat pretty quickly without some forced air ventilation.

> At this particular theater, which dated back to around 1917, they still had one of those old
"Frankenstein's Lab" mercury-vapor rectifiers in place as an 'emergency' DC power back-up.
I fired that thing up once or twice- - it was pretty scary!

[Tim Reed]

Thanks, Jim! Yes, that looks like the Westinghouse rectifier. The Strong unit did operate the fan, which in turn energized the contactor. The knife switch on our machines controlled the fan. I don't remember ours ever getting very hot, either, but copper oxide rectifiers had a time limit of operation. They didn't like anything more than about 20 minutes on at a time.

I'll keep this, thank you. If anyone has literature on the Strong model, I'd be grateful.

[John Eickhof]

tim, can you give me the 'type' designation off the nameplate? i most likely have an original manual

[Tim Reed]

Hi, John. Unfortunately, I don't have the type number. It was this one.... open spoke hand wheel, round fan opening on top, and STRONG on the nameplate (they had one with a solid wheel and squarish fan opening that said MOGUL on the plate).