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Dummy needs help!

Dummy needs Help!

I am trying to connect two LED 12 vdc lights to come on at intervals on a 3 position rotary switch. . . Position 1 = Off. . . Position 2 = One light comes on. . . Position 3 = Both lights come on. . . This doesn't seem too hard except that in Position 2, where only one of the two lights are suppose to light, the power back feeds to the second light through the wiring connected to Position 3 "where both lights are wired together." I have considered using a diode to block the travel of the (12 vdc) voltage in one direction, but I don't know what size diode to get or if size even matters since I am only using 4 to 8 LED 12vdc lights here. I have also considered using a very small 12 vdc relay here, but that seems like a lot of unnecessary work and consumes a little more power and space than I want. Does anybody have any ideas that will help?? Thanks. . .

Reply to
kippymail
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LED's draw very little. I assume you are using LED's designed for 12V with a resistor already inside of them ? If not I suggest you do.

You can use a 1N4000 series type that is good for .5 amps or more as the back feed block.

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Reply to
Jamie

Two - one per each LED.

Cheers! Rich

Reply to
Rich Grise

This will do it for you:

----- +12 ---Vin|LM317|Vout---+ ----- | Adj [62R] | | +----------+---[LED]---+---[LED]---+ | | | o1 | | SW o2----------+ | Gnd ----------------o-->o3----------------------+

The LM317 and 62 ohm resistor fix the current at ~20 mA. For a different current, the resistor value must be changed. The switch determ o1

D1 o2--->|---+--[R]--[LED1]--+ | | SW D2 | | +12 ----------------o-->o3--->|---+ | | | | D3 | +---->|------[R]--[LED2]--+ | Gnd ----------------------------------------------+

The above uses 3 diodes so that LED1 will get the same voltage in position 2 as it gets in position 3, and so that LED2 gets the same voltage as LED1. You could probably use a jumper in place of D1 and D3 and not see any difference.

Ed

Reply to
ehsjr

Put a diode between 2 and 3 instead of the piece of wire you are using. Or use a 2 pole switch.

1 2 3 C 0 0 0 0--- lamp2 --. | | 0 0--0 0--- lamp1 --+-- 0V | | 12V Bye. Jasen
Reply to
Jasen

12V -----[470R]-------------[LED]---+---[LED]---+ | | o1 | | SW o2--[81R]---+ | Gnd ----------------o-->o3----------------------+

Bye. Jasen

Reply to
Jasen

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