We don’t know about you, but we found the Circuitron instructions about wiring lights to a Tortoise confusing. But it’s actually very simple. The picture below shows the wiring to connect a single lamp through a terminal strip. OK, we’ll admit it doesn’t look simple so let’s walk through it.
What we discovered is this: the Tortoise provides pairs of connections that complete a circuit depending on whether a switch is thrown or not. There are eight connection positions on its strip and the outermost (1 and 8) control the motor. So if all you want to do is throw a switch, you connect the outputs from your stationary decoder (a DS52 here) to positions 1 and 8 and you’re in business. That’s what we have running to the left from the DS52 for the loco parking turnout.
If you want to control something else, in our case lighting a lamp when the switch is thrown as in the picture above, you loop your lighting circuit through one of these pairs of positions:
- power to lamp when thrown, no power when not thrown: 3 and 4 or 5 and 7
- no power to lamp when thrown, power when not thrown: 2 and 4 or 5 and 6
If you have Circuitron’s reference page in front of you, its Figure 2 describes condition 1 above, power when thrown.
As we wanted our lamp on when the switch is thrown, we chose the 5/7 pair and wired the lamp circuit through those. To facilitate rewiring, we used a terminal strip for connecting the circuit and tapped the power for it from the DS52 power terminals that serve the Tortoise motor, in the following way from top to bottom on the strip in the picture:
- power from DS52, power to motor connection and position 5 for the lamp circuit
- connection from position 7, connection to one side of the lamp LED
- connection from other motor connection and other side of LED, power return to DS52
I have deliberately stayed away from referring to positive and negative connections, because it gets confusing. When the Tortoise operates, it’s a result of the DS52 switching polarity on the connections, so knowing what’s positive or negative requires knowing also what switch position is intended and that makes it more complicated than is necessary.
What we found easier was to wire it up through the indicated connections, then power the DS52. If the light goes on in the switch position you wanted, you’re done. If it doesn’t, it’s because the LED is sensitive to which side is positive or negative, so all you need do is switch its connections at the terminal strip (turn your stationary decoder off first). We had a 50/50 chance and got it right the first time. If it still doesn’t work, it’s likely just a loose connection or a blown LED (you tested it in advance, right?).
The bottom line is we have an indicator light that lets us know at a glance that the slip switch has been thrown. We will be doing the same for the turnout that controls which siding a loco is routed to for parking (to the left of the slip switch). If you want to have a light on the panel, it’s just a matter of running a pair of wires that far. The Circuitron documentation warns though that you get about a 2 volt loss for every LED so the Tortoise will run more slowly.
This was our first lighting adventure, so of course there were casualties, two LEDs in the waste bin. One of them answered the question: can you take the lamp circuit power off the track bus? Just don’t.