EEVblog Electronics Community Forum

Electronics => Repair => Topic started by: pcmad on December 23, 2019, 11:24:47 pm

Title: led string in parallel
Post by: pcmad on December 23, 2019, 11:24:47 pm

string of led in parallel  20 in the array  led are taking more power than normal and are flickring

testing on multi meter in diode mode show leakage

feeling the led i feel no heat

any tips to find the faulty one with out taking them apart

thank you 

Title: Re: led string in parallel
Post by: German_EE on December 24, 2019, 09:56:57 am

Attach your diode array to a 400mA current limited power supply. SLOWLY increase the current and see which diodes light first, these will be the devices drawing the most current at full brightness.

Running twenty diodes in parallel without matching them first is not a good idea as (as you have found out) some will take more current than others. You need to either a) match the diodes before you solder or b) change your design so that you have a current limiting resistor for each diode.

Title: Re: led string in parallel
Post by: pcmad on December 25, 2019, 10:05:13 pm

thank you found it as you stated also the 20 string led i did not make its came pre made