Wiring red/green 2 pin led's for mimic panel

[disco-dave]

Hi,

 

Can anyone provide a wiring diagram for using bi-colour LED's on a mimic panel to show which way a point is set?

 

What I'm trying to do is use the LED's show green for point set correctly and show red on the line that the point is not set for. I have the power from the track and a wire from the frog which changes to + or - depeding on the direction the point is set. I just need a wiring diagram to show how to wire it up so it works.

 

I've had a search and have found how to do it for 3 pin red/green LED's, but not 2 pin. And as a novice I'm struggling to work it out.

 

I realise you need resistors, but I'm also unsure which ones? The track is DCC using a NCE PowerCab.

 

Any help or a point in the right direction would be appreciated. 

 

Cheers.

[Nigelcliffe]

What you're asking is complicated to achieve. 

It will be far simpler and cheaper to ditch the bicolour LEDs and using tricolour (three legs).  Those are a doddle, as you've found through searching. 

 

- Nigel

[Brian]

Nigel is correct. They require reversing of polarity to change between red and green  This could be done but generally it needs double pole double throw (DPDT) switching arrangement.

 

I personally dislike having red and green point position indications on a panel. There are far too many LEDs lit and it becomes somewhat blinding and possibly confusing too?  IMO all that is needed is one LED per direction (route) lit to show which way the point is set towards and not a second one showing its not set that way!  Then its much simpler to wire and is like the real UK railway which never shows an unset light, only lit or unlit per route direction 

To note; real UK railways do not use green or red indications for point position either, they use white or a yellow indication!   Red and green are reserved for signal aspect indications.

Edited May 24, 2020 by Brian

[Grovenor]

If you use tortoise point motors you can just put the bicolour LED in series with the wire to the point motor, see tortoise instructions.

[John ks]

I agree with Brian & that is how my mimic panel is configured

28 minutes ago, Brian said:

IMO all that is needs is one LED lit to show which way the point is set towards not a second one showing its not set that way!

The drawing shows 2 ways to wire LEDs 

The RH circuit should do what you ask.

But I don't know how the relays (12V coil) will preform at half wave DC derived from DCC

Having a relay across the DCC may interfere with the DCC signal

Every point (relay) will add load to the DCC system

The extra cost of relays

 

It would be possible to add an opto-isolator between the DCC & the relay  

More cost & complexity

 

 

 

The resistor for the LED can be between 1K  & 10K depending on how bright you want the LED

 

John

[Brian]

Hi

 

Just realised you're a DCC user!  As the question is in the non DCC area, I thought you were a DC (Analogue) user!   

You can use your two wire Bi LEDs using the DCC and point frog polarity.  Have a look here Link to item   Scroll down a little.

Edited May 25, 2020 by Brian
Typo corrected