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Old 20-09-2017, 09:06 PM   #11
Walkingthedog
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I think you're missing the point. I don't want random lights going on and off.

An example. There are three houses and three shops. When the houses are lit the shops are dark and vice versa. I hardly ever use the lights on my layout so it would just be a case of occasionally switching them on. It would only require one pair of wires under the buildings.
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Old 20-09-2017, 09:11 PM   #12
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in that case i would use a on-off-on a single pole would do as the negs would all be connected and just have the pos side split one for shops other for houses,
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Old 20-09-2017, 09:18 PM   #13
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OK point taken. I use an old controller to power my lights. Works beautifully. Just thought forward for one set of lights, reverse for the others.
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Old 20-09-2017, 09:24 PM   #14
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ok then, use the controller there should be no problems, no sense in making it more complex than needs be, if you do have problems with failing leds just wire in a couple of diodes,
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Old 20-09-2017, 09:42 PM   #15
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Thanks Mike. LEDs are so cheap it's not a problem if the fail. I shall have a play.
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Old 20-09-2017, 09:51 PM   #16
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WTD you can safely reverse bias a pair of LEDs, bi colour LEDs are exactly that in one package.

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Old 20-09-2017, 10:30 PM   #17
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To answer your specific opening question WTD the leds will not be damaged so long as you dont exceed the max voltage by using suitable current limiting resistors.
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Old 20-09-2017, 10:30 PM   #18
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Thanks Richard. I shall proceed.
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Old 21-09-2017, 02:07 PM   #19
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'Suitable current limiting resistors' will not protect the LEDs in the reverse direction. The reverse voltage typicaly has to be kept below 5V, so if you are running your LEDs from a 5V supply there wil be no problem.

If connecting LEDs in inverse parallel make sure that they share a single current limiting resistor. This will ensure that the reverse voltage on one LED will not exceed the forward voltage of the other which should be below 4V whatever the colour.

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Old 21-09-2017, 02:44 PM   #20
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Thank you one and all. (Not off topic once.........yet)
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