LED strips

[Speedy Builder5Participant @speedybuilder5]

Re cycling LED tube light

[Speedy Builder5Participant @speedybuilder5]

I was given a 4foot long LED tube light with the replacement starter which is in fact a fuse. The wiring instructions said – remove the starter and replace with the LED fuse (Which is the same shape as a starter). But it hadn't worked for the previous owner, and didn't work for me. No problem, so I took it to pieces and decided it was junk. HOWEVER

The LED strip is a string of 96 LEDs, I put a voltmeter on the output of the electronic gubbins and got a reading of 1 volt DC (feeding 240v to the supply side of the unit) – re-connected the LCD strip to the 1 volt output, observing polarity etc. So that did not light up the strip of LEDs ! I tried 1.5 volt, then 9 volt and gave up after that.

Would anyone hazard a guess as to what voltage a strip like that would need? Would the LEDs be driven in parallel or series?

I ask this before I consign the lot to the bin.

[Ian PParticipant @ianp]

You should be able to determine how the LEDs are wired by looking at the copper track (outline visible under the paint layer). I would imagine that they are basically wired in series as each LED will have roughly 3 volts across it.

Why did you decide it was junk?

Ian P

[Ian PParticipant @ianp]

Might be a clue to the arrangement in the number '24S4P' printed on the strip. Maybe 4 parallel strings of 24 LEDs

I'm not familiar with these long arrays in tubes but there will be some current limiting device involved possibly a capacitor

Ian P

[Frances IoMParticipant @francesiom58905]

doesn’t the 24S4P tell you – a string of 24 leds each approx 3V drop across the LED and 4 such groups wired in parallel

There should be a series resistor or possibly a constant current circuit in each group of 24 – my guess is that each 24 group is expected to work from maybe a 110V circuit – there should be some voltage dropper (capacitor usually) or possibly as the LEDs are unidirectional 2 groups are wired might be wired in series and then the 2nd set of 2 groups wired in reverse polarity.

Too good to throw

Edited By Frances IoM on 12/06/2020 17:02:33

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