Electronics > Projects, Designs, and Technical Stuff

Testing LED light strip

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DW1961:
I posted this in another thread, and have another question. I was going to post it in that thread, and now I can't remove this, so well, here it is.

When I test the strips I want to build before installing them in my computer (plugged into the RGB 12V riser), I want to test the strips, of course, for any shorts. But I also want to test it for maximum current draw. So I'm going to just bypass any controllers that come with the strips I am cutting up.

One of you explained how to do it for each color on the strip. That was well taken.

However, if I want to test the strip for maximum current with all RGB diodes on max, should I create a circuit with my MM, and then connect the positive side to the 12v supply, and then tie the RGB cathode sides together on teh neg side to get a maximum current reading? That way the RGB will be operating at maximum current, and I'll know exactly how many amps  so as not to let the smoke out of my motherboard's 2A RGB header.

So something like :

driver 12V+ -->MM--> to 12V+ side of strip

driver neg to all three RGB leads on strip

??

Zero999:
The current meter should be in series with the power supply, connected to the LED strip, with the red, green and blue sections connected in parallel. It doesn't matter whether the meter is on the positive, or negative side of the power supply.

DW1961:

--- Quote from: Zero999 on August 08, 2020, 07:41:57 pm ---The current meter should be in series with the power supply, connected to the LED strip, with the red, green and blue sections connected in parallel. It doesn't matter whether the meter is on the positive, or negative side of the power supply.

--- End quote ---

So, just like I said? And thanks for the meter positioning, as that does make perfect sense.

Can you think of anything else I may want to check on the strip to prevent frying my Motherboard fets?

ozcar:

--- Quote from: DW1961 on August 08, 2020, 09:13:36 pm ---Can you think of anything else I may want to check on the strip to prevent frying my Motherboard fets?

--- End quote ---

In one of your other threads somebody already suggested you could include a fuse in your wiring.

And, a reminder of something else also mentioned in that thread: When measuring current with a DMM, start with the highest range on the meter, particularly if you suspect there could be some problem.

Of course, if you had a bench power supply as was discussed in another of your threads, to test the strip all you would have to do is set the voltage to 12V, set a reasonable current limit, connect the strip and then check the display on the power supply.

RJSV:
Hello, I methodically avoid reading current (but who cares...) So, a heavy duty resister, ceramic 0.47 ohms and the like keeps me out of the 'mistake - trouble happened' syndrome. At a half amp, there's only about 0. 235 or two thirty five milli volts of drop.
  I got impatient, over the years, intolerant of (usually my own) dumb mistakes.
  I also own a 'shunt' : that's a 1 ohm, 100 watt resistor, soldered with a strip of metal:. like 5 mm by 4 cm  (quarter inch wide), with value of 0.012 Ohms !
 

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