[FreeBay] Two ugly old homebrew power supplies..free for the cost of shipping

[Dave Haupt]

Not my best work...the metal work is ugly.

Power supply #1 actually works, as in, it delivers 12.9V, which stays within regulation with a 10 ohm 10W resistor attached.  1970s vintage fake wood-grain cabinet purchased new from Allied Radio Shack in the 1970s.  Transformer is marked "Heyboer 26.8VCT 1.7A...which means I wired it as a full-wave center-tapped device and expected 3 amps or more out of it.  I know darned well I originally built this thing with a Radio Shack transformer, and I also know that I contracted with Heyboer for custom transformers circa 1982 in my first professional job.  So I must have "upgraded" it at some point.  The regulator looks like a 3-terminal device with outboard pass transistor, whose markings have worn off.  I must have been fighting a hum problem, as the filter is 8 electrolytics in parallel on vectorboard.

Photos of "wood grain" power supply:

http://home.comcast.net/~haupt8948/wg1.jpg
http://home.comcast.net/~haupt8948/wg2.jpg
http://home.comcast.net/~haupt8948/wg3.jpg
http://home.comcast.net/~haupt8948/wg4.jpg
http://home.comcast.net/~haupt8948/wg5.jpg

Yes, there are holes in the box that aren't used, and one of the rubber feet is missing.  Also, there's some white paper-like substance stuck to the ridiculously skimpy power cord.  At least I included a fuse.

The second power supply is uglier, if possible, built in a plain aluminum box.  This one used a custom transformer, 35V CT at 1.5A.  The industrial purpose was to create +18V, and +/-15V from one transformer.  For this one, I'd have re-wired it as a full-wave center tap, trying to get 13.8V at 3A out of it...but it actually measures 31V and is not regulated, so I'd say the regulator circuit is blown, but the transformer, diodes, and caps are good.

This one has a 3-prong grounded cord and is also fused.  Photos:

http://home.comcast.net/~haupt8948/alum1.jpg
http://home.comcast.net/~haupt8948/alum2.jpg
http://home.comcast.net/~haupt8948/alum3.jpg
http://home.comcast.net/~haupt8948/alum4.jpg
http://home.comcast.net/~haupt8948/alum5.jpg

I can't tell what the intended circuit of the regulator is on this one, but it doesn't have enough heat-sinking.


Arrangements:

Either power supply ships in a medium flat-rate Priority Mail box ($10.70 in the US), or both in a large flat-rate box ($14.50 in the US).  No charge for the power supplies, just reimburse shipping.

73,

Dave W8NF