Topics

Bi-Polar Red /Green LEDs in Control Panels.

Tom Jones
 

Good morning. I have been using Bi-Color Red Green LED's in multiple control panels on layouts since 1995. I use them in conjunction with tortoise switch motors. 2 LEDs are mounted in parrallel with opposite polarity, controlled by a double pole-double throw miniature toggle with LED resistance provided by the stall current of the tortoise. This is the documentation and wiring suggested on the tortoise packaging. Until my recent experience the green is reasonably bright using my 12 volt/1 amp DC power supplies and the control panels easy to view. I saved all these LED/toggle combinations and have been using them as I build my new layout staring 7 years ago. They work fine. A few months ago I had to purchase more Bi-polar Red/Green LEDs for a new panel. To my frustration the Red is very bright and the Green barely illuminates. I have a couple old combinations from my old layout and they operate the way they did a decade ago. I don't think I bought any different LEDs and my go to businesses have been "Jameco" and "All Electronics". Does anyone have any suggestions on correcting this (maybe higher voltage power supply?) or are the new LEDs so efficient they can no longer be used opposite color back to back in parallel? Thanks for any suggestions you may have that I might try.  I am hoping to not have to rewire the 26 toggles and LEDs on the current control panel.  ...tj

RONALD ST.LAURENT
 

Hi Tom,

I have successfully used a single bi-polar red/green LED for this use.  They are the two leg variety (no 3 leg for this application) attached to the one of the leads to the Tortoise.

Ron

On Sunday, June 28, 2020, 11:48:02 AM EDT, Tom Jones <tomjones4884@...> wrote:


Good morning. I have been using Bi-Color Red Green LED's in multiple control panels on layouts since 1995. I use them in conjunction with tortoise switch motors. 2 LEDs are mounted in parrallel with opposite polarity, controlled by a double pole-double throw miniature toggle with LED resistance provided by the stall current of the tortoise. This is the documentation and wiring suggested on the tortoise packaging. Until my recent experience the green is reasonably bright using my 12 volt/1 amp DC power supplies and the control panels easy to view. I saved all these LED/toggle combinations and have been using them as I build my new layout staring 7 years ago. They work fine. A few months ago I had to purchase more Bi-polar Red/Green LEDs for a new panel. To my frustration the Red is very bright and the Green barely illuminates. I have a couple old combinations from my old layout and they operate the way they did a decade ago. I don't think I bought any different LEDs and my go to businesses have been "Jameco" and "All Electronics". Does anyone have any suggestions on correcting this (maybe higher voltage power supply?) or are the new LEDs so efficient they can no longer be used opposite color back to back in parallel? Thanks for any suggestions you may have that I might try.  I am hoping to not have to rewire the 26 toggles and LEDs on the current control panel.  ...tj

Paul O
 

Tom, I believe you have two options;
#1, an extra dropping resistor in series with the brighter color, or #2, LEDs from a different source.

Paul O

wirefordcc
 

If the LED is in series with the Tortoise motor lead, adding a resistor to dim one of the LEDs may keep the Tortoise from working.

Carl
 

Hi Tom:

My first thought was to use two power supplies, one for Red and one for Green.

The different resistors is a good idea too. Do you have a resistor decade box to try different values?

Carl.

On 6/28/2020 12:49 PM, Paul O wrote:
Tom, I believe you have two options;
#1, an extra dropping resistor in series with the brighter color, or #2, LEDs from a different source.

Paul O

Warren Smith
 


afternoon Everyone:

        I have been using bicolor LEDS with tortoise motors.  I using the secondary switches on the tortoise to control the LEDS.  I do use a separate 5v power supply  and a 220 ohm resistor on the ground leg (using three legged LED's).  This way I can do maintenance on the motors (also have their own power supply) and LEDs without having power to the track.  Hope this helps a little.

Warren

On Sun, Jun 28, 2020 at 1:20 PM Carl <carl.blum@...> wrote:

Hi Tom:

My first thought was to use two power supplies, one for Red and one for Green.

The different resistors is a good idea too. Do you have a resistor decade box to try different values?

Carl.

On 6/28/2020 12:49 PM, Paul O wrote:
Tom, I believe you have two options;
#1, an extra dropping resistor in series with the brighter color, or #2, LEDs from a different source.

Paul O

thomasmclae
 

You may have bought the wrong LED. Confusing as they all have 243 numbers to review.
Look at the LED voltage. It shows the volts for the red/green. Both voltages need to be the same, or one will be brighter. Jamco has voltage as a filter option.
If Red is 1.5 and green is 2.0, the red will be brighter at the same voltage.

Thomas
DeSoto, TX

Tom Jones
 

Paul O;
 I am trying to source different LEDs. I would have to add a dropping resistor on both sides of the 2-legged bi-color LEDs (on the "red" side of each) and a lot of extra work. I wish I had a hundred more of the old ones.  ...tj

Tom Jones
 

Ron, yes a single 2-legged Bi-color red green LED will work and the green will light because it is the only LED getting voltage when DC flows it's direction. Th problem is when 2 Red/Green bi-color LEDs are wired in parallel back to back as on the tortoise discription the Red LED sucks all the power leaving the Green dim or almost not visible.  ...tj

john
 

There are three lead, two color LEDs available and you bias each lead as necessary.

You can use two diodes in series (one reversed), with the bi-color LED and also series an appropriate resistor to dim the red light and another to bios both for the voltage. Remember the diodes cause a .6 volt drop to both colors so consider that in you math. 

Another option, I only light the turnout when it is diverged. 

Hope it helped.

jd


On Monday, June 29, 2020, 03:49:47 PM EDT, Tom Jones <tomjones4884@...> wrote:


Paul O;
 I am trying to source different LEDs. I would have to add a dropping resistor on both sides of the 2-legged bi-color LEDs (on the "red" side of each) and a lot of extra work. I wish I had a hundred more of the old ones.  ...tj

Max Maginness
 

If you wire the two separate LED as shown on the instructions – that is in parallel, “pointing” in opposite directions, ( sometimes known as  reverse parallel) its  exactly the same electrically as if they were on the one 2 lead package.  Or are you somehow using two, single package two lead bi-color leds?

 

Max

 

 

 

From: w4dccqa@groups.io <w4dccqa@groups.io> On Behalf Of Tom Jones
Sent: Monday, June 29, 2020 12:55 PM
To: w4dccqa@groups.io
Subject: Re: [w4dccqa] Bi-Polar Red /Green LEDs in Control Panels.

 

Ron, yes a single 2-legged Bi-color red green LED will work and the green will light because it is the only LED getting voltage when DC flows it's direction. Th problem is when 2 Red/Green bi-color LEDs are wired in parallel back to back as on the tortoise discription the Red LED sucks all the power leaving the Green dim or almost not visible.  ..tj

thomasmclae
 

He is using a pair of red/green two wire LED. We have been using the same configuration for years.
Of the pair, one always shows red, the other green.
We use switchmaster motors, but works the same as Tortoises.
If you but from Jameco (Or non-rail sources) you need to verify that what you are buying has the same voltage for red and green. Otherwise, one color pulls all the amps and the other is dim.
And no way to add a resister to the 'red' as it is the same circuit. (Unless you do a bypass with a diode and resistor, but that would zap the motor (Tortoise) )

Post the Jameco part number, and lets see what the LED specs are,.

Max Maginness
 

Are we getting confused between inserting the bi-color Led in series with one of wires powering the stall machine of either typed and connecting it across (between)  the leads with a resistor in series with the LED.

 

In either case the particular voltage spec of the R or G LED is almost irrelevant – it’s the current passing through them that determines the light output. The only situation where it might matter is if the LED’s are being driven from an very low voltage source like a 3 volt battery, but here we have 12 volts or so.

 

Max

 

From: w4dccqa@groups.io <w4dccqa@groups.io> On Behalf Of thomasmclae via groups.io
Sent: Monday, June 29, 2020 4:00 PM
To: w4dccqa@groups.io
Subject: Re: [w4dccqa] Bi-Polar Red /Green LEDs in Control Panels.

 

He is using a pair of red/green two wire LED. We have been using the same configuration for years.
Of the pair, one always shows red, the other green.
We use switchmaster motors, but works the same as Tortoises.
If you but from Jameco (Or non-rail sources) you need to verify that what you are buying has the same voltage for red and green. Otherwise, one color pulls all the amps and the other is dim.
And no way to add a resister to the 'red' as it is the same circuit. (Unless you do a bypass with a diode and resistor, but that would zap the motor (Tortoise) )

Post the Jameco part number, and lets see what the LED specs are,.

Tom Jones
 

Max, Thomas is correct. Two bi-color in parallel and in reverse direction. The control panel indication is green for route selected, red for not selected.
   Thomas, thank you  for the voltage information on the LEDs. I was not aware of that. I must have gotten lucky years ago when I initially started buying my bi-colors and building control panels. I am out the door camping for a couple days but Friday will investigate Jameco's LEDS and post  my findings.  Thank everyone for there input to the problem. ...tj

thomasmclae
 

Did you try soldering the LEDs in series with each other?
Tortoise left , LED, LED, Tortoise right. With LED short lead to short lead. That way the current path goes through both LEDs, one as red the other as green?
(Better with a diagram, which would take me about 3 days!)
Thomas
DeSoto, TX

Max Maginness
 

A diagram is needed!

Max

 

From: w4dccqa@groups.io <w4dccqa@groups.io> On Behalf Of thomasmclae via groups.io
Sent: Tuesday, June 30, 2020 7:58 AM
To: w4dccqa@groups.io
Subject: Re: [w4dccqa] Bi-Polar Red /Green LEDs in Control Panels.

 

Did you try soldering the LEDs in series with each other?
Tortoise left , LED, LED, Tortoise right. With LED short lead to short lead. That way the current path goes through both LEDs, one as red the other as green?
(Better with a diagram, which would take me about 3 days!)
Thomas
DeSoto, TX

Max Maginness
 

Mind sending me a circuit sketch of this?

 

Max

 

From: w4dccqa@groups.io <w4dccqa@groups.io> On Behalf Of Tom Jones
Sent: Tuesday, June 30, 2020 6:10 AM
To: w4dccqa@groups.io
Subject: Re: [w4dccqa] Bi-Polar Red /Green LEDs in Control Panels.

 

Max, Thomas is correct. Two bi-color in parallel and in reverse direction. The control panel indication is green for route selected, red for not selected.

   Thomas, thank you  for the voltage information on the LEDs. I was not aware of that. I must have gotten lucky years ago when I initially started buying my bi-colors and building control panels. I am out the door camping for a couple days but Friday will investigate Jameco's LEDS and post  my findings.  Thank everyone for there input to the problem. ...tj

 

Max is absolutely correct in that it is current.  If we are talking about a single 2 wire LED that is red when current flows in one direction and green when it flows in the other then it is the fault of the maker to not balance the brightness.

A work around would be to use a different resistor for each direction.  Connect each resistor to a diode in series.  Now connect the resistors and diodes in parallel with the diodes pointing in opposite direction.  Now the current only flows through one resisotr for each polarity.  Now swap out one of the resistors until the brightness is correct.

Best Regards,
Ken Harstine

Don Vollrath
 

Tom Jones, use two of the R/G 2 lead LEDs But connect each of them in opposition series with each other and with one of the Tortoise motor leads. Wire both of the short (or long) leads of the LEDs together. And the opposite pair in series with the motor. Current then will always flow through one Red, and one Green, and be limited by the resistance of the Motor. 

DonV

Carl
 

Hi Gang:

When I was building my turnout motors I used a breadboard like this to test for component values:


SOLDERLESS BREADBOARD, 400 CONTACTS

https://www.allelectronics.com/item/pb-400/solderless-breadboard-400-contacts/1.html

Didn't have problems with the resistors for the LEDs, but did have to add a capacitor to keep the relay from chattering. It is a lot easier to test and fix on the bench, instead of under the layout.

Carl.

On 7/1/2020 1:16 AM, Don Vollrath wrote:

Tom Jones, use two of the R/G 2 lead LEDs But connect each of them in opposition series with each other and with one of the Tortoise motor leads. Wire both of the short (or long) leads of the LEDs together. And the opposite pair in series with the motor. Current then will always flow through one Red, and one Green, and be limited by the resistance of the Motor. 

DonV