I have a number of tomar dwarf signals which are made up of two led's. There is a green and red wire amd a white wire. I used these on a layout I tore down this year and they worked. I made a note "wire red and green to positions 2 and 3 on the tortoise, and the white wire to the common."
I now cannot get them to work. I have about 10 and tried them all and tried with a brand new tortoise.
Any idea what I am doing wrong?
Did the polarity get reversed going to the white wire? That should be + and the red/green on the — side.
Only the — side should be switched at the Tortoise, the + should go directly to the white wire.
I made a little LED tester with a 9V battery and a 1k resistor so I can be sure I have the polarity correct and that the LED is good and the color I need.
I used different resistors to balance the brightness of each color:
Green LED = 390 ohm 1/2w resistor Yellow LED = 560 ohm 1/2w resistor Red LED = 1500 ohm 1/2w resistor
Good Luck, Ed
The attached older thread may give some good background on this.
http://cs.trains.com/mrr/f/744/t/153849.aspx
I have a similar setup where I use the Tortoise to switch the turnout frog polarity with one set of contacts and to switch on layout indicators with the other set. My on-layout indicators are powered by a separate 12v DC power supply, so the contacts reverse the polarity to the indicators. Of course resistors are needed in this case for the LEDs, but I don't recall whether they are built into the indicators or I had to add them.
Please advise what your power source is for the LED indicators, whether resistors are built in or whether you add them to the wiring and how.
Paul
Modeling HO with a transition era UP bent
I agree with Ed. You may have the polarities reversed.
As Ed suggests, you can use a 9v battery to test the dwarfs, but be sure to use a resistor on the red wire and another resistor on the green wire. Otherwise, the LEDs will immediately burn out.
With the 9v battery test, you can only test one LED at a time. Place one of the two resistored wires on one of the battery terminals and the unresistored white wire on the other battery terminal. If the LED does not light, flip the wires to the opposite battery terminals. If the LED still does not light, it is burned out.
Rich
Alton Junction
This is what you need to do. My diagram uses 5-6-7 while you use 4-3-2, but the principle is the same. Make sure that you use 4 as the "center post" for what is effectively a SPDT toggle.
If the wrong LED lights up for the position the points are in, then reverse the wires going to posts 6 & 7 in my diagram, or 2 & 3 in you configuration.
If you "tested" your LEDs without a resistor, you may have seen a brief, bright flash. That is the conversion process for turning a Light Emitting Diode into a Darkness Emitting Diode, or DED.
It takes an iron man to play with a toy iron horse.
If I may make a minor correction for Mister Beasley's diagram, change all the + to - and all the - to +
The Tomar dwarf signals are wired in a common anode arrangement therefore the + has to go to the white + common wire and the - (r-g or r-y) get switched by your Tortoise or any other switch. I prefer to place the resistor, one per LED, on the - side. Again, Tomar suggests 1500Ω on the red and 390Ω on the green.
Some Tomar signals are common cathode where the minus is common but the #H-852 and their ilk are common + anode.
PS: I scanned the instruction sheet but Photobucket is "down for maintenance" so I'll post it asap.
Even if you plan to power the dwarf signal through the Tortoise, I would still test it on a known good 9v battery. Just to be sure that the LEDs are not blown. But, be certain to place a resistor between the battery and the LED being tested.
Many thanks. It now works
I love it when a plan comes together.
And the problem was?