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Electronics => Electronics => Topic started by: spizzak on July 26, 2009, 09:39:58 PM

Title: LED in series
Post by: spizzak on July 26, 2009, 09:39:58 PM
I tried connecting some LEDs in series but for some reason only 2 of them will ever light up at a time. If I connect it the way it is in the picture none will light, but if I connect between 2 or less junctions then those will light. (ie. If i put the 6V across A & C or B & D or C & E the two LEDS in between will light). none of them are burned out and they are all connecting with the correct polarization.

Is it possible to connect LEDs in series or do I need to do it in parallel?

What am I doing wrong?

Thanks!
Title: Re: LED in series
Post by: apc3161 on July 26, 2009, 10:52:51 PM
LED's are obviously a type of diode. Diodes usually have a fixed voltage drop across them (required in order to bias the components to conduct) regardless of current. So it is possible that your voltage is not high enough.

Although to be honest, your numbers sound like you have enough. In any case, usually people put their LED's in parallel. Its easier to control the current going to them this way (by sharing a single resistor) and to make calculations.
Title: Re: LED in series
Post by: SmAsH on July 27, 2009, 01:10:10 AM
1. make sure the polarity is correct...
2. make sure your supply voltage meets the requirements of the led's.
3. make sure no led's are fried...
in my opinion, led and series both have advantages and disadvantages... generally people just go according to their supply voltage and number of led's.
Title: Re: LED in series
Post by: spizzak on July 27, 2009, 07:04:01 AM
thanks guys I guess it wasn't enough voltage, I just ended up putting two sets of two in series in parallel.