Model Train-related Notes Blog -- these are personal notes and musings on the subject of model train control, automation, electronics, or whatever I find interesting.
2020-03-15 - Dwarf Signal for Turnout, ContinuedCategory Train
Here’s a concrete example that shows how to wire LEDs directly to a turnout frog, as explained here, and makes it obvious how trivial this is:
Resistance used here is 1 kΩ, that gives good brightness for both the green and red LEDs.
A 2.2 kΩ resistance also worked well enough for the red LED yet made the green one too dim.
In this example, the frog polarity is switched between rail A and B by a microswitch using the EZ-Track coil mechanism.
Another variation of this that I plan to use on the Randall Model Train layout is to only have the red LED, to make it clear when a turnout is left thrown/divergent. Especially for mainline turnouts, it acts as a “warning” signal. There is no need for the green LED in that case. I will likely embed the LED directly next to the turnout in the ballast. These LEDs are small enough that they could even be placed between the ties. The LED and the resistance can be wired to the existing terminal connected to the auxiliary contracts of the Tortoises.