How to step down power supply

[trickey19]

I have a 60V 20A DC power supply, what I would like to do is keep the original rating of 60V for larger motors but have the ability to step down to about 30V for smaller motors. Is there any way of adding a potentiometer or some kind of voltage regulator or even something more permanent like resistors. Any help would be much appreciated.


P.S. Love the site, great place for beginners.

[pminmo]

What kind of current capacity do you want from the 30V?

Phil

[TigerPilot]

Look at this site. http://www.engineer.gvsu.edu/student...ory/lm138k.pdf
It will only let you use 2.5A I think. Answer Phill's question and maybe something else will have to be done.

Yoram

[abasir]

May be cheaper just to buy new power supply depending on your actual current needs
Dropping the voltage by half means the device (regulator, resistor, etc) must dissipate that power as heat. If your motors requires 30V@10A (300W) then the same amount of heat must be dissipated by the device.

[pminmo]

abasir,
Only with a linear method. Using switching methods, you can drop the voltage with minimal powr loss by the circuit. But it's more complex, but these days it's getting simple enough that even a DIY'er can do it. Reference:
http://www.national.com/appinfo/power/

Phil

[abasir]

I agree with you Phil on the switching step-down. Only thing is, where I am now, it's probably cheaper to get china-made transformer, rectifiers and caps than to get the switching regulator chip and the good quality, high current inductor