signal wiring help needed

[mikebonellisr]

I run on digitrax dcc,use a 10 volt.bi-polar source to operate my tortoise switch machines and am now trying to add 2 color signals to indicate the position of the turnouts.I have added a 1500 ohm resistor to the LED power in lead.By touching different contacts on the tortoise i can get either both lamps to light at the same time,or just the red,or just the green,but I'm not able to switch colors as the turnout is thrown.Pretty sure that it's because of the bi-polar aspect.One set of instructions mentioned wireing the lamps in "reverse parellel"....What the #*&%@# is that?

[Mark R.]

While I'm not familiar with the wiring of the Tortoise machines, I CAN tell you what reverse parallel is, maybe that will help you.

LEDs are polarity sensitive, one leg + and one leg -. To wire them in reverse parallel, you connect the opposite legs of each LED together (+ to - and - to +). Now connect these two combined outputs on the appropriate output terminals on the machine. Seeing as how you're using a bi-polar supply, there MUST be a pair of output terminals that reverse the polarity output when the machine changes position. This will light only one LED at a time as the polarity is reversed - don't forget the resistor on one output side .... either side, it doesn't matter.

Hope this helps !!!

Mark.

[mikebonellisr]

On my way to try it now...burned up a couple of nice oregon signals though
Thanks Mark, it seems simple enough.

[Eriediamond]

QUOTE: Originally posted by Mark R.

While I'm not familiar with the wiring of the Tortoise machines, I CAN tell you what reverse parallel is, maybe that will help you.

LEDs are polarity sensitive, one leg + and one leg -. To wire them in reverse parallel, you connect the opposite legs of each LED together (+ to - and - to +). Now connect these two combined outputs on the appropriate output terminals on the machine. Seeing as how you're using a bi-polar supply, there MUST be a pair of output terminals that reverse the polarity output when the machine changes position. This will light only one LED at a time as the polarity is reversed - don't forget the resistor on one output side .... either side, it doesn't matter.

Hope this helps !!!

Mark.

Not to dispute what Mark stated but just make it a little more clear. It does matter where the resistor is placed. If you tie the positive leads to the LED together, attach the resister to this and the common terminal of the switch, then attach the negative leg of one LED to on side of the switch, then the other LED negative to the other side of the switch, it should work. It may be neccessary to reverse the negative leads if the incorrect lights light, but this way the resistor will service both LEDS. If the resistor is placed in one of the negative leads, it will service only that particular LED, but when the other one is switched on the resistor will not be in that circuit. Hope this helps. Ken

[Mark R.]

Yeah, but Ken, what you're describing is NOT "reverse parallel" which was the original question in the first place !!! You quoted me and still didn't read what I said close enough - ( + to - and - to +) where did I say anything about tying the two positive leads together ??? Describing something totally different does not "make it a little more clear".

Mark.

[mikebonellisr]

I tried it and it worked.I used a set -up that i made a few years ago with a bachmann plastic signal mast, poped out the plastic lenses,inserted red and green LEDs.soldered wires to the leads'insuleted everything with "liquid tape" ran the wires down the mast ,attached the ladder. Connected the Green light + to the red light --,red light+ to green light -,placed a 1500ohm resistor on one set of wires,attached that to the hot leg of the bi-polar (10v) supply and the other set of wires to the negative . It all seems to work.Now I have to try it with more expensive tomar signals.This may cause more problems because it calls for a 360v resistor on the green led and a 1500v resistor on the red led,and only one+ wire(there are 3 in all) Should be fun trying to work it out.

[Mark R.]

The reason for the two values of resistors is the fact that red LEDs are inherintly brighter than green ones. The high value on the red and lower value on the green will give both of them some-what equal brightness. I'm sure you could probably get away with using a common 1000 ohm resistor wired the way I described. The red WILL be brighter than the green, but I don't think it would be that objectionable.

As a side note, when I purchase my LEDs from Mouser or Digikey, I make sure I get red, yellow and green ones all with about the same mcd. rating. This way, I don't have to fool around with different resistors on each color trying to balance the brightness - 1000 ohms works great on 'em all !!!

Mark.

[Eriediamond]

My appologies Mark. Only excuse I can give is that I didn't have my second cup of coffee. Ken

[mikebonellisr]

MCD rating? I,m just getting the hang of bi-polar,ohms resistance ratings,reverse parallel,spdt,dpdt,etc.,etc. It's going to be a l o n g 2006 as i work on my signals but with help from you guys,I'm looking foward to it.Thanks for all of your help,and please be patient with all the dumb questions.

[Mark R.]

Mike - mcd. rating is the lumenous intensity in a given direction.

"cd" is the abreviation for candela or one candle power.
"m" is the abreviation for milli - Latin "mille" for one thousand.

Thusly, for example, a 3 mcd. rated LED produces 3000 candle-power at its brightest point. A .03 mcd. rated LED would produce 30 candle-power.

Mark.

[Don Gibson]

QUOTE: ... I Connected the Green light + to the red light --,red light+ to green light -,placed a 1500ohm resistor on one set of wires,attached that to the hot leg of the bi-polar (10v) supply and the other set of wires to the negative . It all seems to work...

I think the confusion is using the +/- bi polar supply with (polar) LED's.
If you feed the LED'S from the Totoise SPDT contact's and terminate them in a common ground, it may work with the negative side of the supply. If not, reverse the common and positive lead's. I don't think the LED's will discriminate. USE two resistor's though, as Mark suggested (They're cheap).

[Mark R.]

I think "bi-polar" is what's confusing a lot of people. The Tortoise has two sets of SPDT auxiliary contacts - pins 2,3,4 and 5,6,7 with 4 and 5 being the common to each. By using one set of aux. contacts and a bi-polar supply, a two-color signal can be wired using only two wires from the tower. The diagram below SHOWS how to wire this ....



Mark

[mikebonellisr]

And here-in lies the problem,the tortise drive(10v bi-polar,DC) is connected to pins 1 & 8.
The track power to power the frog (12 -16 volt (AC ?) from my digitrax chief dcc,is connected to pins 7, 6, and 5. with a jumper from pin 5 to pin 4,I now have power to use the pins 2 & 3 but it will be AC,as is the frog power.This works o.k, with some NJ International signals that I've had laying around for years(they're marked for 4.99 each)
They are a little too bright.....Do resistors also work on AC bulbs? Also I am getting the hang of hooking up the LEDs,but now I found that the tomar LED signals have only 3 wires green for the green light ,red for the red light and a black.I cant figure out how this completes a circuit

[nbrodar]

The Tomar signals have a green control, red control, and a ground. In this case, you'll need to connect the positive of the supply to pin 5, the red and green leads to pin 6 and 7, and black lead to ground. (I think) Don't forget the resistors.

I make my own signals, so I wire them to run directly off the machine's power supply, without using the contacts.

Nick

[Mark R.]

Mike, hmmmm, now I'm confused !! First of all, you originally stated you're using a bi-polar power supply .... I'm beginning to think you're not (?) The diagram below shows how a bi-polar supply is built ....



Second, I don't understand the jumper between pins 4 and 5. This tells me you're using the DCC track voltage to run your signals. I personally wouldn't do this. Rather, use a separate power source to operate your signals.

Third, the three wires you describe on your tower would be as follows -
Red - positive lead to red LED
Green - positve lead to green LED
Black - common negative lead to BOTH LEDs.
IF you are using a true bi-polar supply, you will have to re-wire the LEDs in the tower as described earlier .... I assume you don't want to do that.

The simplest approach would be to use a single source power supply - not a bi-polar one. Connect the black signal wire to the neg. terminal. Connect the positve supply to pin 4. Finally, connect the red and green signal wires to pins 2 and 3 - you may have to reverse these to get the proper indication for the route you have. This way, you can install the recommended value of resistor for each of the two LEDs individually.

Lastly, for what it's worth, resistors CAN be used if you power LEDs with AC. LEDs are designed to work on DC, so when powering them on AC, they are only lit on half of the AC cycle. It has been learned that LEDs life span is shortened using AC due to the rapid on/off cycles (fast enough the human eye can barely detect it). While DCC track voltage IS AC, it's not the same as typical house current. AC house current cycles at 60 hertz while the AC current found in typical DCC systems cycles between 300 and 400 hertz. This higher rate, I believe, would be even more detrimental than standard AC supplies.

Mark.

[mikebonellisr]

Mark
It appears that I'm going to have to make a decision about which way to go with the signals.I don't want to re-wire the LEDs that I have
It may be clearer if I mentioned that the bi-polar supply first goes to a toggle then to pin 8
I have a +
a-
and a +/- on the toggle.which controls the direction of point travel
I don't need that jumper on pin 4,as right now it's just suppling another source of power for any 12 volt usage,such as bulb signals.But if I use LEDs I can use those 3 contacts for any DC application

and a +/ -

[Anonymous]

Mike,

One of your posts said you're using Oregon signals. If they're the 2-color 2-led type, there's a much easier way. And you don't have to use the relays on the Tortoise.

However you get power to pins 1 and 8 of the Tortoise, it's DC. One is positive, the other negative. When you reverse them, the tortoise motor runs in the opposite direction.

LEDs only work in one direction -- swap positive and negative and they don't light at all.

So what I find easiest is to connect one LED's anode to the other's cathode via a common wire. Then the other contact of each LED to the proper resistor. Then connect both resistors together (on the other side of the LEDs).

Then I guess -- connect the resistors to one of the wires going to the Tortoise and the common wire to the other. One LED will light, the other will not. Throw the switch that reverses the polarity to the Tortoise and eureka! the one that was on goes off, the one that was off comes on. If I guessed wrong (which I seem to do about 80% of the time), I just reverse them!

When making the signals, I put 2 wires, red and green or yellow and green, between each LED and it's resistor, so I can drop the resistors below the layout along with the black wire.

I use the Tortoise relays for power routing, and put 8-position terminal blocks under the layout so I have a screw connection to the Tortoise. That way, I can solder an 8-wire cable to the Tortoise once, on the workbench where I can see it. Then I make all the power, turnout, and signal connections to the same terminal block.

[dinwitty]

you have to reverse polarity to the LED's to get green or red, this is the same thing for single LED's with 2 colors in them, one red one green element in reversec connection, put AC on it and you get yellow.

Its one less wire but unless the tortoise hase DPDT capability, you cant do it simply.
You would have to drive a relay to DPDT a reverse polarity to the signal.
or else an electronic driver circuit.

I use Wire Wrap wire for signal wiring, or you could use enameled wired to keep the wire size really small and not have shorts.
Just take time and do it right.

[Anonymous]

QUOTE: Originally posted by dinwitty

you have to reverse polarity to the LED's to get green or red, this is the same thing for single LED's with 2 colors in them, one red one green element in reversec connection, put AC on it and you get yellow.

Its one less wire but unless the tortoise hase DPDT capability, you cant do it simply.
You would have to drive a relay to DPDT a reverse polarity to the signal.
or else an electronic driver circuit.

Dinwitty, I must not understand what you're saying, or I didn't explain myself well. My method reverses polarity to the signal very simply -- using the same 2-wire circuit that reverses the polarity to the Tortoise motor (pins 1 and 8). No relay needed.

[mikebonellisr]

A couple of things that I THINK i found out.
I do have a bi-polar supply to operate the tortoise.The toggle on facia,which throws the points by way of the tortoise, has a 1000 ohm resistor on it.It seems that I don't have to have resistors on the LEDs as the resistor on the supply has already been reduced.
I have two really cheap LED signals hooked up and working.They are on a single track section,facing away from each other and both show the correct switch position.
I'm also going to take your suggestion about using terminal strips ,My back is killing me and it's a real bear trying to solder above your head,using 24 guage wire in and around the other wires(The + and - DCC power bus ,the 3 wire tortise power/control. the wire to power the frog, drops from the track to the DCC bus,The loconet cable)Trying not to burn anything or myself with a hot iron.But when I threw the switch and it all worked...it was great!Just one little thing,not a major problem,but curious...as the turnout is thrown,the signal gets a little brighter,then dims when the throw is completed.

[Anonymous]

Here's an even easier way, without resistors:

http://tonystrains.com/technews/tortoise/wiring-leds.htm