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Author Topic: Selecting & Wiring Resistors for LED Building Lights - Advice Needed  (Read 484 times)

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Offline IanF

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Re: Selecting & Wiring Resistors for LED Building Lights - Advice Needed
« Reply #15 on: March 20, 2020, 07:46:38 PM »
@REGP   nope, totally irrelevant which way round you connect a resistor, and indeed doesn't matter whether it's on the positive or negative side of the LED in the circuit.     Just be consistent when you connect them up, for your own sanity sense of tidiness!

When I'm fitting a bank of resistors to a circuit board I tend align them with the colour bands and tolerance band reading left to right.

The answer to this may be somewhere on this thread but I thought I'd ask.
Can you use a single resistor on a number of the same forward voltage diodes or do you require a resistor for each diode? :dunce:
Help - I don't know what I'm doing

Online ntpntpntp

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Re: Selecting & Wiring Resistors for LED Building Lights - Advice Needed
« Reply #16 on: March 20, 2020, 07:57:10 PM »
Can you use a single resistor on a number of the same forward voltage diodes or do you require a resistor for each diode? :dunce:

Are you wiring the LEDs in series or parallel?   

If in parallel you should use a resistor per LED, it avoids any problems with slight differences in the forward voltages of the LEDs (could cause some LEDs to light up and others not).  Plus with a single resistor trying to supply all the LEDs would mean you need to calculate for a larger total current, maybe even to the point of needing a higher wattage resistor. and if one LED fails the others will then draw too much current.  Resistors cost pennies, no need to skimp on them.

If wiring in series then one resistor is fine, calculated to limit the current based on the total forward voltage - and of course your supply voltage must be greater than that total forward voltage.
« Last Edit: March 20, 2020, 07:59:26 PM by ntpntpntp »
Nick.   2016 celebrating the 20th anniversary of "Königshafen" exhibition layout!

Offline IanF

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Re: Selecting & Wiring Resistors for LED Building Lights - Advice Needed
« Reply #17 on: March 20, 2020, 08:00:56 PM »
Series - so I guess a few in one circuit is best - could feed off a busbar for each circuit? (DC system not DCC)
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Online ntpntpntp

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Re: Selecting & Wiring Resistors for LED Building Lights - Advice Needed
« Reply #18 on: March 20, 2020, 08:04:43 PM »
@IanF    With my streetlights I've wired 3 in series with one resistor, to run off 12V supply.  Four might work if the forward voltage total isn't too high, but I prefer to allow some overhead.   It's more efficient to share the current through multiple LEDs if you can.
Nick.   2016 celebrating the 20th anniversary of "Königshafen" exhibition layout!

 

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