How to... 12v filtered dc 4A to 5dc

[jjnorth]

I picked up a 12v dc filtered power supply at a garage sale today and was wondering how to go about making it so it would put out 5v dc. Or even variable. Wanted to use it to power some breadboard projects for my classes this year. thanks for any advice.

 

[alec_t]

Not enough info provided. Check for any model names/marks/numbers and Google those. Hopefully you'll be able to get a datasheet for the supply. Without that, unless someone on the forum has knowledge of the internals of the particular supply we can only guess at solutions.

 

[jjnorth]

specs

It is a staco model FPS-4
current rating 4A
120 VAC input 60HZ 72 Watts
output 12VDC 4A
When I measure the output terminals(with a voltmeter)it is just over 16V is that due to RMS values?

 

[Reloadron]

My guess is what you have is a filtered but not regulated 12 volt 4 Amp power supply. A transformer, a full wave diode bridge, and filter capacitor(s). The output voltage you measured would support that. If the input voltage was 120 VAC the output would be 12 volts * 1.414 or about 17 Volts. That would be the peak voltage the capacitor(s) charge to. A slightly below 120 Volts input would yield a lower output so it fits. Remember there is no regulation.

Now if you look at the data sheet for the LM317 family of regulators you will see around page 17 how to make yourself a nice 4 Amp or so adjustable regulated power supply working with what I thin you have.

Ron