PSU test circuit design....HELP!!

[Goomba79]

Hello,
I have been asked to make a little test box to check if a PSU is working correctly.

The box needs to light a green LED if the correct voltage and current is present
and light a red LED if the voltage is incorrect.

I have no idea where to start with this, i have some electronics experience but I have never had to design /make anything

I know it is probably really simple but I have no clue where to start!

Thanks for looking and any help offered!

iain

[kbs]

Hi,

The easiest way to test the current is to calculate the (minimum) load resistance (R = V/I).
Then connect a reistor of that value across the output. Ensure the resistors Wattage is high enough and be prepared for heat! W = V mutiplied by A (allow a little extra to prevent phenomial temperatures in the resistor as this can melt the solder!)
You can now test that the voltage is correct at that load. Let me know if you require more info on this, but I guess you can find plenty of 'battery monitoring' circuits that switch LEDs on/off at your required voltage.

NOTE: this approach only tests the supply voltage at full load, do you also need to test for 'voltage out of range' at lower loads?

Kb