A little while back i was watching a Youtube video where the person attached a switch and an LED to one of the feeder wires of a rail that was segregated in the yard. This way if you have a loco waiting you do not have the sound starting or to pull any power by having the loco sit with sound on. I want to do this with the three tracks in my engine service area on the layout. However i cannot find the video to look back at it.
I have an NCE powercab system 2 amp system.
A few questions
This can be done on either one of the feeders going to this isolated track? My understanding is if one feeder is not working (due to the switch) and the other is powered the DCC decoder will not work
Is there any harm to the decoder to have one rail powered and the other not?
Would the correct circuit for this settup be (Bus-Feeder-Switch- Resistor-LED-Feeder-Track)
What type of Resistor, LED and switch would i need?
No - the resistor with LED would go between the track side of the switch and the other rail that you din’t put the switch in. An LED in series with the feeder like you wrote it will actually block half the DCC signal. If you want an LED to indicate that a given track is powered, what you need is an LED in series with a resistor, adn the combo connected across the track you want to indicate power for.
For the switch,a ll you need is a basic SPST toggle switch, with just 2 connections on the back. Power comes in on one terminal fromt he bus, goes out to teh track ont eh other (doesn;t matter which). Witht he switch int eh Off position - no power to the track, with the switch int he On position, track has power.
LEDs, pick one, whatever color you like to indicate the power is on. And unless you manage to get some more specialized ultra high efficiency LEDs, a 1K ohm 1/8 watt resistor will work.
Switch in series on one of the feeders. The resistor and LED in series, wired between the two rails. So when you turn off the track, you’re also turning off the LED;
1K 1/4 watt resistor, whatever kind of LED strikes your fancy, and just about any SPST toggle switch.
As an aside, I have several storage tracks with shutoff switches, but I didn’t bother with LED’s. Why waste the DCC power? Instead, I just installed the switches so flipped UP means the track is hot, and switched Down means it’s off.
That actually gives you the advantage of knowing if a loco is spanning the gaps - If the switch is down, but the track is powered anyway, you have something bridging the gaps.
But if all you look at is the LED, it just tells you the track is hot. It could be switched on, or it could have something spanning the gaps.
Thanks for the advice, i will probably just use a SPST toggle by itself then. Saves a few dollars on not having to buy LEDs and resistors.
I dont think i will use LEDs for this now, but would it really take that much power from the DCC system? I thought LEDs were suppsosed to have very low power usage
For the number of LEDs that you are talking to indicate track power the drain on the DCC system will be negligable, and they won’t likely all be on at the same time anyhow.
For structure lighting you should have a separate power supply(s).