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Is it possible to attach an LED to an SMB? Answered

I have a QI charger with a PCB and it has 2 surface mounted LEDs, one red and one green.

Is it possible to attach some wire and then a traditional LED to this point, rather than using the SMB?  I tried to simply put the LED pins onto the SMB solder but to no avail.


The SM LED may run on less current than the through hole LED so make sure the LEDs are compatible.

If you add the through hole in parallel with the SM LED they will share the current and it may not be enough current to run the two LEDs so remove the SM LED if you want to use the through hole LED.

Make sure the through hole LED is mounted forwards bias and you have a clean and solid soldered joint. It may look like a good joint but in fact you may not have contact at all.

OK - I shall give this a go. Is there a way to find out the current of the SM and what the LED needs?

Most LEDs run from 5 to 20 ma but some go as high as 350 ma.

You can try to get the datasheets for the LEDs from the maker, or these sites:



If that fails measure the voltage across the LEDs resistor. Then the current is voltage divided by the resistor in ohms.

SMD resistors are marked like 104 or 1 is the first digit 0 is the second digit and 4 is the multiplier so 104 would be 100000 ohms or 100 kΩ. 33R would be 33 Ω and 4R7 would be 4.7 Ω 000 is a bridge 0 Ω.

Should be OK with a fine tip soldering iron. make sure the new LED is the right way round.

You may not get good results with 2 LEDS in parallel - in fact you should not do this. Remove the SM LED then replace with a wired LED.