working signals

[mikebonellisr]

Guys
Don't make it sound too easy....You'll embarass me.
Thanks

[rrinker]

If you are powering the LEDs directly from the DCC bus, and you are not using a bi-color LED (just individual red and green ones that aren't connected to one another other than a single common point - in other words, using a signal with two seperate indications rather than a single targe that turns red or green), then you shoudl put an ordinary 1N4001 type diode across the LED, wired in the opposite direction, AND you will likely need a much larger resistor than a 300 ohm. 300 ohms at a DCC track voltage of 15v allows 43ma or more throught the LED - WAY too much! Use a 1K resistor instead, that's more like 14ma.
The extra diode is because excessive reverse voltage (in this case, with 15v at the track, 15v) will destroy an LED slowly but surely.

An easy way to have indications like that with a Tortoise is to put the LEDs back to back (connect anode of one to cathode of the other, and vice-versa) and wire this pair in SERIES with one of the motor leads on the Tortoise (pin 1 or pin 8, doesn't really matter). One of the two LEDs will glow dimly as the switch moves, and then when it stalls the LED will glow brightly. The Tortoise stall current is around 10-15ma, which is perfectly safe for an LED. If the red and green indications are backward, just reverse the wires to the LED pair.

--Randy

[cwclark]

the led's should work fine, but you'll need to put in a resistor (180 to 300 ohm should work fine) so they don't blow out and also, the current flows only one way through them so if they don't light up the first time then reverse the wire leads and they should light..the tortoise is a perfect UTTSM because it has a built in DP/DT switch which can be used to light the targets...I've lit many targets with LEDs using atlas relays and tortoise machines with a resistor wired in series with them.....Chuck

[mikebonellisr]

While your here....I just need a simple signal system that will show me the direction of turnouts.I'm using DCC with Tortoise switch motors.I've tried a couple of signals but they either didn't light,only stayed one color or blew out completly.I've tried LEDs and 12 v bulbs....What will work?

[cacole]

If you're going to run DCC, check Digitrax' new plug-n-play signal system.

[cwclark]

here is a good train detection circuit project and they don't cost no more than $10.00 a piece to build...surf around this website..there are three parts to this circuit you'll need to complete the circuit http://www.gatewaynmra.org/detection1.htm if you want them pre-built then check out Loy's Toys..they have a lot of prebuilt train detection circuits, so does Dallee and Circuitron

[cwclark]

there are three types that are popular...one of the oldest is the "Twin T" train detection circuit which senses a resistance across the rails and operates relays to change the signaling target lights...another one uses nad gates which fall out and switch the lights when there is a voltage change in the block and then there are the ones that use light such as photocells or infared sensors...they are way too complicated to explain here but there are a lot of good books out there to show you how to build them..."Electronic projects for model railroaders" is a good one and just a second..i'll get you a website to one you can scratchbuild with step by step instructions..i'll post it here shortly...chuck

[mgruber]

I'm rebuilding my layout and want to add working searchlight block signals. Any ideas on what detection system to use and what signals?][?]