I laid out the original 1977 Hot Cake a while back, but never got around to doing the modern one that came out in 2003. So here's the newer one. I ignored the original relay bypass switch and the polarity protection diode could be replaced with a 1N4001 or similar. The original 1N5238 is an 8.2v zener. It's laid out for board mounted pots as usual, and should be an easy fit in a 1590B. Here's the schematic for reference.
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