You Know You Are Old When

[CalG]

I still have a lot of selenium rectifiers. All different sizes, some full wave, assorted voltage and current ratings.

Last week end, I halped a friend repair his standby generator set. An old "power company" Onan with a nice diesel engine.
It was only putting out 70 volts per leg.

It's a transformer regulated device, and a look at the schematic showed that the most likely, or at least the lowest hanging fruit would be the bridge rectifier that supplies the exciter. Sure enough, replacing that device brought the output to just under 250V leg to leg.
My friend was amazed that I happened to have such a component "just kicking around" in my shop. ;-)

 

[Fuddyduddy1952]

It's been over 50 years since I had some Electronics Engineering but from memory () I seem to remember the forward voltage drop for germanium was about 0.3V, silicon about 0.65V, and selenium about 1 volt per stack. So I would replace a defective selenium with silicon for many reasons.

 

[CalG]

I've contemplated making a DC output for my ANCIENT buzz box welder.

But have not yet found a problem that AC stick could not handle. Barring TIG needs!

 

[Fuddyduddy1952]

I've contemplated making a DC output for my ANCIENT buzz box welder.

But have not yet found a problem that AC stick could not handle. Barring TIG needs!

If it's like my Lincoln 225A stick welder, you would need one heck of a hefty diode!

 

[WinterDeere]

If it's like my Lincoln 225A stick welder, you would need one heck of a hefty diode!View attachment 4492057

Best Croc Dundee accent: That's not a diode! THIS is a diode: https://siliconpower.com/diode_specsheets/sdd303kt.pdf

lol... one of my first jobs as a young robotics engineer was designing, building, and process engineering wafer probing and scraping systems for testing diodes up to 5000 amps for SPCO. Their diodes look like tuna fish cans!

Basic idea, to hit very high currents, they'd put 10,000 or 20,000 N-P junctions in parallel, between a pair of 3" or 4" diameter metal plates. My job was to build the machines that would test every junction, and then scrape the solder paste off the contacts for the bad ones, before they complete the assembly operation.