Linear Driver current without testload?

So i was reading around this forum, and stumbled upon one thread that said that you could test the current of a linear driver without a test load. It didn't go into much detail so i'm kind of confused. Could you just hook up the driver to the diode and put a multimeter at the connection?



-Thanks

furrylaser said:

So i was reading around this forum, and stumbled upon one thread that said that you could test the current of a linear driver without a test load. It didn't go into much detail so i'm kind of confused. Could you just hook up the driver to the diode and put a multimeter at the connection?



-Thanks

Click to expand...

Yes you can....

That being said... You risk blowing your LD if any DMM
connection to the circuit is intermittent for even a fraction
of a second while powered... or you inadvertently go
over the LD's max current rating.

The safest way to test/adjust the current of a Laser Driver
is to use a Test Load. After all that's what they were designed
for...


Jerry

You can test with your ammeter in place of the diode. If you want to test with your diode in place, it is far better to test current on the driver's input. Input current = output current. This way if you disconnect something by accident, the circuit just shuts off and no harm is done.

The rkcstr driver lets you set the current by using your DMM and measuring between a couple points on the driver. Never used one so I can't say how accurate that is vs. a test load.

What Cyparagon said will work too but you can get the parts to make a test load for like 8 bucks at rat shack. (yes you can get the parts cheaper online but by the time you pay and wait for shipping to Hawaii [I hate you btw ] it's probably cheaper at rat shack)

You can also test the output of a driver by directly connecting it to a multimeter in current measuring mode. Surely the output voltage would be near zero in such a case, but the current should be whatever you have set it to - if your driver does a proper job, that is.

Obviously it will dissipate more power then when driving a diode that has a voltage drop, so be careful that it doesnt overheat... this should not be a problem if you test it only for a few seconds though.