I plan on using Tortoise switch machines for my layout and I have searched for and read all of the Tortoise related threads. There’s plenty of good information, but no mention of the rating for the LED’s. I plan to use a bi-color LED in-line from connection 1 on the switch machine to the toggle switch. Do I need a 12V LED if I use a 12V power supply? It appears that 90% of the LED’s I find are 1.8V/2.2V. The few 12V bi-color LED’s that I have found have been over $3.00 a piece, no thanks.
Any Bi-Polar LED in series with the Tortise power will work just fine.
The Tortise acts as the current limiting resistor. A Tortise draws about 15 ma(.015 Amp) in the stalled mode. That is within the specs of most any LED, Bi-Polar or otherwise.
The Tortise manufacturer recommends using the above method.
If you instead choose to wire the LED using the built-in switches and a separate power source then use a 750 to 1000 Ohm resistor in series with the LED.
My major source for all LED’s can be found in this link:
Radio Shack sells red LEDs with the necessary resistor already included. Look for part # 276-270. They’re available in green and orange as well. Also included in the package, is the mounting hardware. I’ve been using these LEDs for several years, and haven’t had problems with them. If you use a pair wired in series, they’ll change direction when you throw the switch.
BTW, an old train-set transformer can be used to power your Tortoise machines, along with the lights.
When wiring an LED in series with the Tortoise motor, you don’t need a resistor, and you don’t want “12v” or “5v” LEDs (which are just ordinary LEDs with resistors already in them). One toggle switch lead goes tot he tortois emotor lead. The other toggle switch goes to one leg of the bi-color LED, and the other leg of the LED goes to the other motor terminal. Done. In one direction, the LED will be red, int he other, green. If it’s backwards (red when it should be green), just reverse the LED leads OR the tortoise motor leads.
If you want to use the switch contacts on the Tortoise to activate LEDs, then they do need resistors. The value varies depending on the power supply you use in this case. Here you could use the 12v LEDs with a 12v DC power source. However, it is usually cheaper to buy ordinary LEDs in bulk as well as (in the case of a 12v supply) 1K resistors.
This is an either/or situation - if you want LED indicators you can do either of the above things, but there’s no need to do both. LEDs in series witht he tortoise, without resistors, works just fine and is simple. It’s one of the big advantages of the Tortoise motors that you can do this.
I was also thinking about using the internal switches on the tortoise to control the LED. As you pointed out in a previous thread, this would be a true indication of track alignment. Would I use one set (2,3 & 4) for the LED wiring and use the other set (5,6 & 7) for powering the frog (DCC)?
What would be a good value for a resistor on 9V power supply?
Most LED’s need current limiting resistors to limit the Amperage to 20 ma or less. Generally 1K (1000 ohms) is used with a 12 volt DC supply.
Bi polars (R) (G) can make ‘cool’ idicators but you’ll need a Bi-Polar (+/-) power supply or DPDT contacts to do. (The ‘Tortoise’ switching machine may only have SPDT’s). I am using DPDT toggles with 12 voltsto throw my stall-mortor’s and also feeding bi-polar indicators through 1K resistors. Works. Benefit is single hole for LED plus single toggle does all.
A Transformer without rectification will make R +G go YELLOW.
If $3 is too steep for you, go to separate RG LEDs. Unfortunately cheape
For LEDs you can use a 3V – 12V power supply. I also confirmed this when I got home. I hooked up the power pack and set it for 9V and the Tortoise would run back and forth with the flip of the direction slider. Then I hooked up the bi-color LED in line on one side (connection 1 on the Tortoise). The Tortoise would go back and forth like before and the LED would change color as it should. I checked the voltage and it indicated ~7V. A drop of 2 volts like Randy indicated in a previous thread. So, this works near perfect. The only flaw is that it’s not a guarantee of turnout alignment. Hooking up the LED to one of the internal switches would guarantee the indicator was correct. I do understand that a resistor is needed for the LED on the internal switch.
I found the bi-color LEDs I need for $0.28 each on Jameco.
Now I just need to figure out how to utilize to internal switch for the LED.
Well, so do the ones in series witht he motor. They are on dim while the motor runs and brighten up when it stalls. There aren’t human lives at stake here so I think it’s close enough.
A 470 or 560 ohm resistor would be fine for a 9 volt power supply.
HAVING Micro switches depressed by the actuating rod; or assembled on Rix-Rak II with Switchmaster/Hankscraft motors, will give you an ‘accurate’ real-time reading when the switch is actuated.
I DO HAVE a +/- 12V.power supply. I also have some Swithcraft / Hankscraft motors assembled with microswitches to give me real-time indication, I just decided R.T.postioning - where desirable - may not be necessary. I may change my mind. Simplicity may not be best.
Since I do not have any Tortoise machines, I have to back off on how their on-board electrical contacts are wired - and did. I know they are good machines. I surmise that there is a 1K voltage dropping resistor in series with the motor which will accomodate LED hookups on 12 volts.
Randy’s remark re: dimming - when moto is turning is interesting.The voltage is dropping? Would a bigger resistor or separate resistor feed bypassing the motor cure this?
Yes, LED’s will work on 2.2V.with proper current limiting. Power supplies can also vary a great deal if unregulated, and most aren’t. I set my LED’s @ 10-12 ma. current, changing the resistors, - regardless of the voltage. They should last longer than on 20ma. I have found they DO burn out. Better than a lightbulb, though.
I use this setup (LEDs wired in series with tortoise) and actually like that they dim while the switch is throwing. When they come back to full brightness it’s a good indication the turnout is done throwing - useful for hidden turnouts in particular, but even just for ones with view blocked by a building, train, etc.
PS - I get all my parts (toggles, LEDs, etc.) from this fellow and have always been very happy with price and service both:
There is NO RESISTOR within the Tortise machine. The Tortise motor serves as the current limiter. In fact there are no electronic components within the Tortise. Just a motor, a printed circuit board DPDT switch and some gears. That is why they are so reliable and easy to install.
As stated, Tortoise do not use any resistors, unlike the Switchcraft motors. The LED dimmign is because the current draw drops even lower whent he motor is moving. I should use my trick ‘new’ (it’s actually some 20 years old) Fluke meter and check the running current of the Tortoise. Stalled is 15ma or so - this is why you cna just put an LED in series. Running it probably drops below 10ma. My cheapy $5 special meter probably can;t see the difference, but the Fluke has the accuracy for it. I could also try taking my all-purpose experimental Tortoise (which has been disassembled and abused for over 15 years) apart and lettign the motor run free with no gears attached and see whatthe current draw is. It’s totall silent - it’s the gears that make the noise in a Tortoise - and I suspect the current draw will be in the single digits.