LED Switch Position Indicators

[ncng]

I have been installing LED switch position indicators in my control panels. The problem I am having is that sometimes, not always, both LEDs for a switch are illuminated. I am using the relay in a Tortoise switch machine with a positive input, a negative input, and a single output to the two LEDs. The output is run to the anode side of one LED and the cathode of the other LED. It appears to me that there is leakage backwards through the LEDs. Is this a correct assumption? Is there a way to prevent this problem?


[This message has been edited by ncng (edited 20 May 2000).]

[ChrisDante]

<BLOCKQUOTE>quote:</font><HR>Originally posted by ncng:
I have been installing LED switch position indicators in my control panels. The problem I am having is that sometimes, not always, both LEDs for a switch are illuminated. I am using the relay in a Tortoise switch machine with a positive input, a negative input, and a single output to the two LEDs. The output is run to the anode side of one LED and the cathode of the other LED. It appears to me that there is leakage backwards through the LEDs. Is this a correct assumption? Is there a way to prevent this problem?


[This message has been edited by ncng (edited 20 May 2000).]<HR></BLOCKQUOTE>
It sounds like you are using two separate LED's instead of one bi color LED. Is this correct? ( I will assume so). What is the purpose of the relay? I use Tortoise machines, bi-polar DC (I believe that was option 2 in the Tortoise instructions) bi color LED's, SPDT switches, my power supply is 9.5V both + & -, and no relays.

I need more info.


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When in doubt, empty your magazine.

[ChrisDante]

<BLOCKQUOTE>quote:</font><HR>Originally posted by ncng:
I have been installing LED switch position indicators in my control panels. The problem I am having is that sometimes, not always, both LEDs for a switch are illuminated. I am using the relay in a Tortoise switch machine with a positive input, a negative input, and a single output to the two LEDs. The output is run to the anode side of one LED and the cathode of the other LED. It appears to me that there is leakage backwards through the LEDs. Is this a correct assumption? Is there a way to prevent this problem?


[This message has been edited by ncng (edited 20 May 2000).]<HR></BLOCKQUOTE>
Here's a thought...
1. when you have both LEDs lit take a volt meter and find out which way the current is flowing. Do this on one of your switches that are operating correctly as well so you have a good constant.
2. try reversing one of the LEDs see if that changes anything.

LOL

[ncng]

Yes I am using two separate LEDs not a single bi-color LED. I use SPDT switches with center off. This allows me to leave the switch in the center off position when not changing switch position and still show turnout position. I use one of the built in SPDT relays (pins 5,6 & 7) to control the polarity to the LEDs. I use regulated and filtered 5 VDC to power the LEDs. Each LED has a 270 ohm resistor attached to drop the current to about 2 volts.

I have verified that the polarity switches and the voltage remains constant when changing the turnout position.

[ChrisDante]

You are fast approaching my limit of electrical knowledge.

But here's another try.

LEDs should only light when voltage is flowing in one direction. IE if the annode is on side A(side A refers to the way you have them wired) then it will light if the annode is on side B than it will not light. LEDs are current direction sensitive. their illumination is dependendent upon the direction of the current. If both are lighting at the same time check current flow and find one that is working correctly duplicate that wiring onto one that is not working correctly and see if that helps.

LOL

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When in doubt, empty your magazine.