Hello, I'm new to the forum and wondering if anyone has used prewired led's that have the resistor as a part of it with a Tortoise? I know you don't need the resistor with that switch, but the only prewired led's I could find had it installed. Would another option be to wire the led to the switch? Paul
Welcome to TrainBoard, Paul! You ALWAYS need resistors for LEDs, to limit the current going through them. The only other way is to ensure that the voltage to the circuit is just above the LEDs forward voltage drop. Since different LEDs have different ratings... ALWAYS use resistors.
I'm not sure if I understand the situation, but I wanted to offer up a link to 12VDC LEDs that have a built-in resistor at https://www.allelectronics.com/category/340600/leds/12-vdc-leds/1.html These are 5mm (T-1 3/4) $0.50 Ea. The same size LED without the built-in resistor is $0.15 Ea and resistors are $0.065 Ea. Proceeding with Rick's suggestion provides a solution at half the cost if that is of concern.
The Tortoise instructions state that LEDs can be used with a TORTOISE without resistors. The instructions say: "... the low current draw of the TORTOISE allows you to wire Light Emitting Diodes (LEDs) directly in series with the motor." I've read this elsewhere as well. I do not use TORTOISEs myself, so I have never had occasion to test this. Naturally, this runs counter to my decades of experience with LEDs! TORTOISE instructions: http://www.circuitron.com/index_files/ins/800-6000ins.pdf - Jeff
Having no experience with TORTOISEs, I was not aware that their motors draw so little current. - Jeff
You might want to try one and see if it works. Remember that the motor will be stalled at the end of the machine's travel, so you will always be passing current through the LED and resistor. Do you know the wattage rating and the resistor value used?? The LED may be too dim when the motor is moving, or the switch machine may move too slowly.
I have installed a Tortoise with no resistor. I put a two lead bi-color red/green LED in series with one lead. Green for straight and red for diverging. Max current is around maybe 19 ma last I remember. Many I know have done this with no resistor. Some like to use nine volts for little slower point operation. Your choice. Rich
The LED that has the resistor already wired, what voltage is it intended for? 12V? Is it a single color LED, or a bicolor? If the resistor/LED operating voltage is the same or similar to your supply voltage for the Tortoise, just connect it in parallel with the Tortoise' motor connections. If the LED is bicolor it will light one color in one position, the other in the 2nd. If it's a single color LED, it will be lit in one direction, dark in the other. In the 2nd case, you could use two different LEDs (one color different than the other) wired in anti-parallel to get a corresponding color for point position. The tortoise was designed in part for its own resistance to be appropriate for LEDs, but one minor warning. Modern LEDs are significantly more efficient than those from the days of the Tortoise's implementation. A stalled Tortoise with 12V applied is roughly 20mA as others have said. Some of the modern high efficiency LEDs are well driven and bright at 5mA, and have a 20mA MAXIMUM allowed safe current. If that's true with these LEDS, you are driving them hard. Their lifetime will be shorter than if you drove them at 5mA. This warning applies only to the LEDS you might wire in series with the Tortoise motor without resistors of course. Lyle
All of my Tortoise motors have two leg LED's installed with no resistor, and they've been working great for over a year.
