I have 28V power supply with max current 3.5A.I want load the power supply from 0A to 3.5A through rheostat and current consumtion and voltage should be displayed. one idea is to rheostat but it will consume more power and size.
so help me how to implement this in more smart way.

 

You'd need a pretty high wattage rheostat. Just wire it to the center wiper with a current meter in series.

You'd need a 100 watt rheostat and they do not come cheap.
http://www.radionics.ie/electronic-components-ie/1/718160398-RHEOSTAT-100W-1K.html

This may be of interest.
http://ece.okstate.edu/abet/Assessm...stone Reports/PowerSupplyLoadAnalysisTool.pdf
You could modify the load circuit to provide a varibable manual controlled one.

 

I have 28V power supply with max current 3.5A.I want load the power supply from 0A to 3.5A through rheostat and current consumtion and voltage should be displayed. one idea is to rheostat but it will consume more power and size.
so help me how to implement this in more smart way.

What you are looking for is called an electronic load (or current sink). An electronic
load uses a MOSFET and heatsink to dissipate the power. I have an example schematic
and PCB layout at http://www.luciani.org/geda/util/matrix.pdf

(* jcl *)

 

nice schematic john. dynaload used to make a variable load test equipment device which was used to make the testing and adjustment of power supplies easy. however when a quick test was needed, we would use a piece of metal banding strap (1" wide x 75' long), the stuff they use to tie down pallets. i imagine you could use a smaller size. we ran 2 beefy wires to it with stak-ons and bolts to cleaned surfaces. i can't remember the resistance, but was easy to calculate everything from there for a quick test. not pretty but worked.

 

'pretty' is highly overrated

 

nice schematic john. dynaload used to make a variable load test equipment device which was used to make the testing and adjustment of power supplies easy.

Thanks.

For low voltage (<100V) loads I like the Kikusui and the HP (now Agilent) loads.

(* jcl *)