current sink as replacement for rheostat

[sabu31]

Hi

I have to use a rheostat of 0-500ohms and 300W rating for testing a circuit. As i dont have it, is it possible to replace the rheostat function using any variable current sink circuit.Any references for such current sinks ?.I am sorry if question is silly.. Thanking you.

 

[alexan_e]

how is the rheostat supposed to be connected, is it against ground as a load?
what kind of circuit will it be connected to , are the voltages AD or DC?
Give some more details.

Alex

 

[sabu31]

HI

Sorry i didnt give the details. The load is to be connect directly across a solar panel as a load. I actually wanted to measure charactersitics of solar panel. But i am confused as solar panel also acts as a current source... if using current sink to test the charactersitics is advisable.

 

[kcyang]

Hi Sabu,

What you need is a two-quadrant (or four-quadrant) power supply. You characterize your solar panel by sweeping the four-quadrant power supply voltage and measure the solar panel current. This is the solar IV curve.

 

[sabu31]

Hi
Thanks for the reply.. I was looking for a circuit which i could make.. THe panel rating is 200V Voc, and Isc=3A.. So the current sink should be able to sink in 3A ... and also work at 200V at open circuit condition..

 

[kcyang]

If you want to build it youself, I recommend you to build a constant-voltge electronic load. It is very similar to a shunt voltage regulator. I quickly Google a few webpages:

**broken link removed**
**broken link removed**

The easiest way is to buy an electronic load that has a constandt-voltage mode. Most of them do have such a mode.

 

[sabu31]

If you want to build it youself, I recommend you to build a constant-voltge electronic load. It is very similar to a shunt voltage regulator. I quickly Google a few webpages:

**broken link removed**
**broken link removed**

The easiest way is to buy an electronic load that has a constandt-voltage mode. Most of them do have such a mode.

Thanks for the help.I will try out shunt regulator.. But rather than buying electronic load.. rheostat would be cheaper..