Instructables

Step 3: Circuit Explanation

Picture of Circuit Explanation
I am working with a 70 light string which consists of two parallel circuits that have 35 lights each in series.  When one of the LED's fails the circuit breaks which affect all the other lights (half of them) that are in the same series circuit.

Another factor to consider is the current limit of an LED.  LED's do not like a lot of current so besides the LED there is also a current limiting resistor in each light.  For this repair we are actually going to bypass the faulty light.  This will increase the current that goes through the remaining lights because we have eliminated part of the resistance.  However, taking one light out should not increase the current enough to damage the remaining LED's in same circuit.  There is of course a limit.  Bypassing any more that two lights in the same series circuit will likely increase the current enough to put the remaining LED lights in jeopardy which will definitely destroy the entire half of the light string.
 
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