Regulated power supply and electronic equipment

[shredgd]

Hi,
I have successfully built a regulated power supply featuring an LM317T voltage regulator (see the schematic of the "Small Wart" at SmallBear).
Maybe it is a silly question, but I'm wondering, if I use it to run a cd player or some other electronic equipment (of course setting it at the indicated voltage), which normally works ok with an unregulated voltage supply, will it (i.e. the regulated power supply) damage it (i.e. the electronic equipment)?
My doubt is related to the fact I won't have the typical voltage drop you get with an unregulated power supply with a load connected, so there might be excess voltage somewhere.

By the way, I built the power supply starting from an unregulated one I had at home: I simply ripped off the part of the circuit board which didn't contain the transformer and added a small piece of perfboard with the regulating circuit. I think this is the fastest, easiest and cheapest way to build the thing (instead of starting from scratch)! I also kept the polarity switch and the multi-plug lead (including a 9v battery snap!) the adapter had, for maximum versatility!
As my transformer secondaries put out 14.4v AC, I decided to simply put a 2.2k trim pot (to which I managed to have access from the outside) between the LM317T adjust pin and ground (instead of a 1.1k resistor in series with a 500 ohm trim pot): this way I can have from 1.25v to 12.7v DC! To keep things simple I decided to leave the "dead battery option" and LED indicator parts off.

Giulio

[smoguzbenjamin]

I don't think it should be a problem, I used a regulated wallwart (that squealed at me with pedals) with my discman and that worked fine...

I think it would be fine... no garuantees though.  :roll:

[Peter Snowberg]

Hi Giulio,

Equipment that takes an unregulated supply will normally have a regulator inside it. You will not damage it as long as you feed it with a similar voltage it would get from the unregulated supply. The only thing you have to watch for is drawing too much current from the LM317. If you don't get a burn form touching it, everything is good. Linear regulators can producing an amazing amount of heat. If you are going to draw lots of current from it, just use a good heat sink.

Take care,
-Peter

[shredgd]

Thank you!