LED indicator for testing LED string to find out if the string is open

[budm]

I just build this for troubleshooting to find out if one or more LEDs of the LED string is open. It is connected in line with the LED string wire without having to find the polarity of the output first, you can use DCA meter to test too but the meter may not show fast enough before the circuit goes into protection shutdown.
You will put this in one string at a time to find out which one does not light up the LED.
The diode string will get warm when 500mA (Power = 0.6V x 500mA) flows through the diode string.
One of the LED will light up if the string is not open.

[tom66]

Re: LED indicator for testing LED string to find out if the string is open

Do you have a schematic for this jig? Looks interesting, but hard to see how it is wired up.

[eccerr0r]

Re: LED indicator for testing LED string to find out if the string is open

It looks like two subcircuits in antiparallel:
Subcircuit is three 1N4001's in series, and a LED + resistor in parallel with the three 1N4001's. The 1N4001's will drop about 2.1V which is enough to light the LED when they're conducting. If you connect the other way, the antiparallel subcircuit will light.

I think I would just use a faster ammeter to tell if the circuit is open or not though...

[budm]

Re: LED indicator for testing LED string to find out if the string is open

I build this because lots of people here does not understand to how use meter in AMP mode when I told them to put meter in AMP mode, visual indicator is much easy to see if the LED even flashes on or not.