I had been using batteries and battery packs with clip leads to power transistor radios so I needed to build this anyways.
I have a Lambda LP-532-FM Adjustable 40 volt 3 amp regulated power supply, but it is way to big and heavy for my bench.
So I built this:
A project case.
old power cord and strain relief.
A transformer that outputs 28vac.
15 volt dc meter.
2 amp bridge rectifier pulled from some electronic device.
2200uf 50v electrolytic cap.
.1uf 50v film cap.
120 ohm resistor.
5k pot (I did not have a 3k).
LM317T adjustable voltage regulator.
1 amp fuse on the output side of the transformer.
old SPST power switch.
1 tie point.
There is still room for a milliamp meter.
There is a jumper so I can hook in my DMM as a milliamp meter.
The maximum voltage output is about 35 volts but I will not be using it over 12 volts. The el cheapo DC volt meter is pretty accurate.
I checked the heat sink last night while powering my Ray Jefferson 630rdf and noted that it was indeed too small. I rectified that problem but then broke a lead on the LM317T and had to get a new one this morning.
I think the new heat sink should be more than adequate, no?
Here is the Schematic: