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3 prong Bi-Color Led wiring help please

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3 prong Bi-Color Led wiring help please
Posted by gdelmoro on Thursday, January 23, 2020 7:21 AM

hi all, I have some bi-color led's that have 3 prongs. 

I'm using DPDT Toggles to control Tortose Switch Machines with a 12v DC Power Supply.

Not sure if I wire the LED to the switch or the Tortoise or HOW to do it. I find schematics for 2 Pin but not 3pin.

Anyone have a wiring diagram they can share?

Gary

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Posted by RR_Mel on Thursday, January 23, 2020 8:07 AM

Use one of the Tortoise SPDT switches .

 

 
 
Mel
 
 
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
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Posted by richhotrain on Thursday, January 23, 2020 8:13 AM

On a 3-leg bi-polar LED, the resistor goes on the center leg.

Wire the outside legs of the LED to the 6 and 7 (or 2 and 3) leads on the Tortoise. Wire the 5 (or 4) lead on the Tortoise to one side of the DC power pack and wire the center leg of the LED to the other side of the DC power pack. That will complete the circuit.

Rich

Alton Junction

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Posted by rrinker on Thursday, January 23, 2020 9:57 AM

 3 lead ones have to be driven as shown above. Benefit, they will always glow full brightness. Downside - more wiring, at least if you are putting these in as panel indicators. If you are making signals right at the turnout, then it's not so bad, the wires just have to run up from the Tortoise to the layout surface.

2 wire bi-color LEDs, you just put them in series with the wire goign to pin 1 or pin 8 of the Tortoise. Less wiring, no resistors, but they do glow dim while the Tortoise is moving, and then go bright when it stops in position. And they reduce the voltage to the Tortoise, whichs lows it down (not always a bad thing).

You can always do both - stick the 2 wire kind on your control panel, use the 3 wire ones out on the layout as signals.

Think of the 3 wire kind as two individual LEDs, which is exactly what they are, two LEDs with either the cathodes or anodes tied together. The two wire type are two individual LEDs wires antiparallel to one another.

                                             --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by gdelmoro on Thursday, January 23, 2020 10:33 AM

Thanks.  You guys always help.

Gary

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Posted by gdelmoro on Thursday, January 23, 2020 1:03 PM

When i power the Tortoise from the DC Power bus to positions 1 & 8 does the tortoise power the internal switches or do I need to also power the internal switches? As if they were stand Alone?

Gary

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Posted by richhotrain on Thursday, January 23, 2020 1:19 PM

gdelmoro

When i power the Tortoise from the DC Power bus to positions 1 & 8 does the tortoise power the internal switches or do I need to also power the internal switches? As if they were stand Alone? 

Wiring the DPDT to 1 and 8 are sufficient to power the Tortoise in order to throw the point rails. To power the internal switches, you need to wire either 2, 3 and 4 or 5, 6 and 7.

Rich

Alton Junction

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Posted by RR_Mel on Thursday, January 23, 2020 1:41 PM

You could power the LEDs from the Tortoise power using a full wave rectifier such as a DB107.
 
 
 
 
The Rails side is the ~ on the DB107.  Connect the ~ terminals to the Tortoise motor 1 & 8 then it will output +12 and -12 to drive your LEDs.
 
 
 
 
Mel
 
 
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 
 
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Posted by rrinker on Thursday, January 23, 2020 2:30 PM

gdelmoro

When i power the Tortoise from the DC Power bus to positions 1 & 8 does the tortoise power the internal switches or do I need to also power the internal switches? As if they were stand Alone?

 

The switches internal to the Tortoise are standalong, they are in no wat electrically connected to pins 1 and 8. The moving contact (equivalent to one of the center pins of you DPDT) is either pin 4 or pin 5, depending on which of the two internal switches you use. You need to feed power in per Mel's diagram above.

I was momentarily confused by the bridge rectifier thing, but now I get what Mel is sayng. The way a Tortoise works, when it's turned one way, pin 1 is + and pin 8 is -. When you change to the other position, now pin 1 is - and pin 8 is +. If you connect one ~ terminal to 8, and the other ~ to pin 1, then the terminal of the rectifier labeled + will always be + no matter which way the TOrtoise is, and the termina llabeled - will always be -. Combining the diagrams, with the LEDs you have, the - would go to the resistor and then the commin center pin of the LED. The + would go to pin 4 on the Tortoise. Pin 2 would go to the red LED lead, pin 3 to the green LED terminal. If the red and green are backwards, reverse the connections on pins 2 and 3.

That's one option, to not have to run an extra power supply out to the Tortoises. For panel LEDs though, I still say the 2 wire type are the easiest to install with minimal wiring.

                                                    --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
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Posted by gdelmoro on Thursday, January 23, 2020 3:26 PM

Thanks for the replies!

Mel, that's too much for me. i'll just wire like Rich said.

I apprciate the info and maybe some day I'll take some time to learn more. 

Gary

  • Member since
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  • From: Cresskill, NJ USA
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Posted by gdelmoro on Friday, January 24, 2020 6:08 AM

richhotrain

On a 3-leg bi-polar LED, the resistor goes on the center leg.

Wire the outside legs of the LED to the 6 and 7 (or 2 and 3) leads on the Tortoise. Wire the 5 (or 4) lead on the Tortoise to one side of the DC power pack and wire the center leg of the LED to the other side of the DC power pack. That will complete the circuit.

Rich

 

Last question (for now Big Smile), these LED's are 1.3VDC and my bus is 12VDC what capacity resistor is orrect?  They came with 450  470.

Gary

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Posted by richhotrain on Friday, January 24, 2020 6:19 AM

gdelmoro
 
richhotrain

On a 3-leg bi-polar LED, the resistor goes on the center leg.

Wire the outside legs of the LED to the 6 and 7 (or 2 and 3) leads on the Tortoise. Wire the 5 (or 4) lead on the Tortoise to one side of the DC power pack and wire the center leg of the LED to the other side of the DC power pack. That will complete the circuit.

Rich 

Last question (for now Big Smile), these LED's are 1.3VDC and my bus is 12VDC what capacity resistor is correct?  They came with 450  470. 

It depends upon how bright you want the LEDs to be. The resistors that came with the LEDs are sufficient to protect the LEDs from burnout using a 12 VDC power supply, but the LEDs will be pretty bright at that low level of resistance. My practice is to install 1K ohm resistors on my LEDs to tone down the brightness a little.

Rich

Alton Junction

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Posted by rrinker on Friday, January 24, 2020 7:24 AM

470 ohm is too small for a constant 12 volts, that's over 22ma to the LED. 1K is what you want. 

                             --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    September 2004
  • From: Dearborn Station
  • 18,804 posts
Posted by richhotrain on Friday, January 24, 2020 7:51 AM

rrinker

470 ohm is too small for a constant 12 volts, that's over 22ma to the LED. 1K is what you want. 

                             --Randy 

Something that has surprised me, just by experimenting, is how high the resistance can be and still have acceptable LED brightness. I have tried 2.2K and 3.3K resistors, and the LED brightness is still acceptable.

Rich

Alton Junction

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  • From: Cresskill, NJ USA
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Posted by gdelmoro on Friday, January 24, 2020 2:38 PM

Thanks Randy and Rich

Gary

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