Where should this LED go?!

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centenary
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Where should this LED go?!

Post by centenary »

Not sure I can explain this accurately so, hope folks can follow what Im asking!

Ive had a sub mimic \ control panel schematic printed for the less busy side of the layout. See below.
Screenshot from 2025-06-22 15-55-35.png
My query is the best place for the point position indicator LEDs for the bottom RED line and last RED point on the right of the schematic.

I can only control 2 LEDs so any suggestion of using 3 LEDs doesnt work for me. The direction of travel on the bottom RED line is left to right. Usually, Id position the LEDs on each of the point's 2 routes. However, because it's a facing point with normal direction of travel, left to right, Id position 1 LED between the top 2 RED points so locos travelling the 'wrong way' can access the 2 sidings.

For any loco travelling left to right on the bottom RED line, where should the second LED go? Should it be on the other leg of the same point (which is where Id normally expect it to be) or, should it go on the short straight after the last RED point and curve at top right?

Thoughts gratefully received!
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Flashbang
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Re: Where should this LED go?!

Post by Flashbang »

I assume you want point position LEDs? If so, then two LEDs per point. One lights for the straight-ahead route and the other lights for the turnout route. Direction of travel is unimportant. Its the position of the point that's needed to be known.

You only need one series resistor if the two LEDs per point are the same colour i.e. Yellow or Green etc. Feed each points pair of LEDs with a positive DC supply via a point operated change-over switch. Join together the two Cathode LED leads (Shorter of the two) and connect them to one end of a series resistor The value of which in Ohms is determined by the supply voltage, so for 12v DC I would use a resistor in the range of 1K to 2K2 (1000 to 2200 Ohm) at 1/4 watt. The other end of the resistor connects to the supply negative.
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aleopardstail
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Re: Where should this LED go?!

Post by aleopardstail »

personally if you have four LED control signals, two per point (well one switch per point) I'd be wiring them in series to work with three LEDs
three lines.png
failing that go with as Flashbang suggests, LEDs after each point
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centenary
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Re: Where should this LED go?!

Post by centenary »

Flashbang wrote: Sun Jun 22, 2025 5:25 pm I assume you want point position LEDs? If so, then two LEDs per point. One lights for the straight-ahead route and the other lights for the turnout route. Direction of travel is unimportant. Its the position of the point that's needed to be known.

You only need one series resistor if the two LEDs per point are the same colour i.e. Yellow or Green etc. Feed each points pair of LEDs with a positive DC supply via a point operated change-over switch. Join together the two Cathode LED leads (Shorter of the two) and connect them to one end of a series resistor The value of which in Ohms is determined by the supply voltage, so for 12v DC I would use a resistor in the range of 1K to 2K2 (1000 to 2200 Ohm) at 1/4 watt. The other end of the resistor connects to the supply negative.

Untitled.jpg
Sorry, my description wasnt the best. The LEDs are to show route set which by inference means the way the points are set rather than pure point indication.

Thanks for the confirmations, that's where Id put the LEDs.

As regards wiring them etc, on this section of the layout, these points will be DCC Concepts pre wired switches and LEDS so no mucking about with resistors and cathodes (thankfully!).

The rest of the layout, approx 24 points, will be controlled with MPC System 2.
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