Hopefully someone with more knowledge of power supplies can answer this. I've built a variable DC power supply based on the LM317 regulator to power my guitar effects. I have a wall wart with 20VAC output connected to a full bridge rectifier I made from individual diodes. The rest of the circuit is one of the designs I've seen for the LM317. Some of the designs I've seen have additional diodes across the 3 pins of the regulator and some don't. Mine doesn't. When I power the circuit up, the DC voltage out responds well (~2-24VDC) when I turn the adjustment pot. The problem is that I also have an AC component that also responds to turning the pot. I understand that ripple can occur, but the AC voltage goes a high as 70v! Is this normal? I'd hate to fry one of my guitar effects. Any thoughts would be greatly appreciated.
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