Increased current capacity

[rookee]

I wanted to increase the capacity of a bench top power supply with variable voltage. If I went with 3-4 317's in parallel in this circuit http://www.wikihow.com/Add-Variable-Voltage-to-Your-ATX-Based-Bench-Power-Supply - what is the easiest way w/o having to build 3 complete separate circuits.
I'm sure I want to use just the one pot in parallel with the 317's, but I'm over thinking this and starting to confuse myself.
Can someone help me out?
Thank you,
Confuse Rookee

[Chippie]

rookee,

Using the attached schematic, connect the resistors and transistor, replace the 3 terminal regulator with your LM317 scheme....You could just use one reg instead of the three you have already connected...

The current flowing thru the 1R resistor turns on the transistor when the current exceeds around 650 ma....Put the transistor on a heat sink....

[rookee]

Thanks alot I appreciate it.

[Chippie]

Glad I could help...nice to be appreciated... ;)

Any problems contact me via pm..

[microgyros]

A pin-for-pin replacement would be the 5 amp LM338T. It would retain a 5 amp over current limit where the "piggyback" method would have no thermal or short circuit protection.
It would maintain regulation with a marginally lower input to output voltage.

To make room on my bench,I just bought several universal (12 to 24 volt,70 watt) switch-mode laptop power supplies.I replaced my benchtop unit soldering iron station and all manner of power supplies.They are brilliant......very quiet,efficient and compact as they are 30+kHZ not 60Hz
You can get 5 to 12 volt versions too,all regulating at +/- 5%.:cool:

For audio or motor drive applications or powering fast chargers you may need a substantial reservoir capacitor at 2,200 uF/amp even although these units output regulated d.c.
mike

[rookee]

Thanks for the offer Chip and the additional advice micro. The 338 is mentioned on the page; I was just trying to avoid yet another shipping charge from mouser as I had some 317's laying around. Definately would be better than piggybacking 3X 317. I must have been really tired that night 'cause looking back at the hand drawn image shows it would be really easy to stack the 317's "on top" for simple parallel use.

I will bookmark this page for when I order more parts from mouser :o .

Something funny for you - overheard here somewhere - 'I consider local electronics employees to be a step above McDonalds'. I sent my son to RS for some parts and actually wrote down exactly what I wanted. He came back with different parts because they didn't have anything I needed - a higher resistor than I wanted, not lower or I could have tied a couple together, and my favorite - instead of .1, a .01 cap because it is "the closest we have".
I do get tired and I do confuse easily; but I almost lost control of my bladder over that.
Thanks again U2.