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Old 20-09-2017, 09:04 PM   #1
Walkingthedog
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Default A question about LEDs

Now LEDs only work if the current passes through them in one direction.

If I wired some LEDs in parallel some one way round and some the other way round only the correct ones would light. If I then reversed the direction of the current the LEDs that were alight would go out and the others would light.

Does it damage LEDs if they are connected to the current the wrong way round?
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Old 20-09-2017, 09:10 PM   #2
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I believe best practice is to connect them the right way round and not to reverse the current. If not they may have a shorter life.
In practice I don't think it makes a great deal of difference. If you wanted to be absolutely sure I suppose you could include a diode in the circuit?
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Old 20-09-2017, 09:12 PM   #3
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they should be fine, i have wired up some of my loco directional lighting like that,
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Old 20-09-2017, 09:17 PM   #4
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The reason I ask is because I am thinking of wiring lighting some building this way. One set of buildings would be alight, reverse the current, they fall dark and the others light up.
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Old 20-09-2017, 09:23 PM   #5
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Brian, what are you like with electronics as you can create pulsing effects using 555 timers, and the delay can be set for long on/off periods,
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Old 20-09-2017, 09:33 PM   #6
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I have absolutly no idea what that means. I just want to occasionally light up some buildings, just thought it would be an easy way to add a bit of variety. I know I could do it with two separate circuits but just want to find out if LEDs wired the wrong way round will be damaged if current is applied for 20 minutes or so.

You can explain what you were talking about later if you wish Mike, always ready to learn
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Old 20-09-2017, 09:37 PM   #7
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the leds will be fine, you could use a larger resistor on the leds if you want to,

no problem Brian, when i get there i will be doing a similar circuit for flashing lights etc, same principle, just a slight variation of resistor values,
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Old 20-09-2017, 09:51 PM   #8
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Why not wire the LEDs correctly but switch the separate circuits with a DPDT switch.................HB
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Old 20-09-2017, 09:53 PM   #9
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I probably will but was just wondering if my suggestion will work or will damage the LEDs.
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Old 20-09-2017, 10:00 PM   #10
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what about using latching reed switches placed at a couple of areas of the track, and have a couple of items of rolling stock fitted with magnets, you can't get much more random than that once the stock gets shifted about a bit,
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