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12 volt grain of wheat bulb to DCC / reverse loop

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  • Member since
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  • From: Louisville
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12 volt grain of wheat bulb to DCC / reverse loop
Posted by dbduck on Monday, February 27, 2023 3:37 PM

can a 9-12 volt grain of wheat lamp (70ma) be  hooked directly to Digitrax DCC track voltage with the  use of a properly sized voltage dropping resistor, I am thinking  56 ohm for about a 4 volt drop?

My intent is to attach  red & green lamps  between  main track & a reversing loop (see diagrams) to indicate if  polarity (phasing)  between them is correct / incorrect before proceeding over the gap

 I guess in reality, I would only need one resistor since  only one lamp would be getting power at any given time

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Posted by wvgca on Monday, February 27, 2023 4:09 PM

you might be better off to add some bridges in there to give you DC out, remember that DCC doesn't change polarity, it changes phases, direction change is done via the information packets sent along with the DCC power feed ..

  • Member since
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Posted by dbduck on Monday, February 27, 2023 4:12 PM

wvgca

you might be better off to add some bridges in there to give you DC out, remember that DCC doesn't change polarity, it changes phases, direction change is done via the information packets sent along with the DCC power feed ..

 

true but as for as I know the track phasing does not change as for as  Rail A & Rail B Thus the need for a "reversing circuit" of some sort to bring the phasing in line between the two tracks

I guess my main question is, would the attachment of the lamps affect digital information packets being sent along the rails?

  • Member since
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Posted by CSX Robert on Monday, February 27, 2023 9:46 PM

Yes, that will work and will not affect the DCC signal. 

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Posted by dennis461 on Monday, February 27, 2023 10:06 PM

My DC layout, I used LED's for that. When I converted to DCC, I left them connected.

I think I have a diode bridged connected also.

 

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Posted by maxman on Monday, February 27, 2023 10:47 PM

If one installs one of those DCC reversers, then I don't think one needs to worry about any of that reversing stuff nor is there a need for any polarity indicators.

Or am I incorrect?

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Posted by richhotrain on Monday, February 27, 2023 11:17 PM

maxman

If one installs one of those DCC reversers, then I don't think one needs to worry about any of that reversing stuff nor is there a need for any polarity indicators.

Or am I incorrect?

You are correct. I use PSX-ARs, and an LED on the circuit board flashes when the auto-reverser is activated. As long as the auto-reverser is functioning properly, there is no need for any sort of trackside signal.
 
Rich

Alton Junction

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Posted by dbduck on Monday, February 27, 2023 11:28 PM

maxman

If one installs one of those DCC reversers, then I don't think one needs to worry about any of that reversing stuff nor is there a need for any polarity indicators.

Or am I incorrect?

 

you are correct as far as trackside signaling not needed if using an auto reversing device.

call me old school, but I'd rather have manual control over the reversing loop, besides why should I go out and buy an auto -reversing unit when I could accomplish the same thing with about $3 Worth of parts, I already have. Also, the reversing toggle switch is already installed, My concern was whether or not the lamps would interfere with the data packets

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Posted by maxman on Tuesday, February 28, 2023 12:04 AM

Well, for one thing you would not need to have to stop the train in the loop while you did the toggle switching thing.

I think you can enter the loop from either direction, which I always thought was an issue with the toggle thing.

Also, it was never really clear to me how trains approaching the loop following the first train would be affected by the polarity (phase?) change.

But I guess all that is off topic.

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Posted by dbduck on Tuesday, February 28, 2023 12:24 AM

maxman

Well, for one thing you would not need to have to stop the train in the loop while you did the toggle switching thing.

I think you can enter the loop from either direction, which I always thought was an issue with the toggle thing.

Also, it was never really clear to me how trains approaching the loop following the first train would be affected by the polarity (phase?) change.

But I guess all that is off topic.

 

you do not need to stop the train to switch phasing while the train is in the reversing section with DCC, since phase reversing does not effect the direction of the locomotive as polarity switching would in DC

The manual switching performs the same operation as the auto reversers.

with regard to trains following each other, The reversing section would be set for the train to enter  at point A, once the train is in the section, the phasing can be switched so that the train can exit at point B at the correct phasing.

once the first train has exited the section, the section is then re-aligned to be correct phase for the next train to enter at point A

The phase reversing process is repeated for each train

 With auto reversing, the switching of the phasing for the reversing section is done by the device as the train enters & leaves the section automatically 

 

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Posted by richhotrain on Tuesday, February 28, 2023 3:35 AM

Yeah, that is the thing to keep in mind about a reversing section. It must be fully gapped and isolated from the track at either end of the reversing section.

So, once the entire train is inside the reversing section, a manual toggle switch can be thrown without stopping the train so that the track inside the reversing section electrically matches the the track outside the reversing section.

The problem with manual switches is that you have to remember which way the reversing section is set electrically at any given time to prevent a short when the train enters or exits the reversing section.

The OP is looking for a solution to remind him at all times how the reversing section is set electrically by setting up a system of trackside signals.

Rich

Alton Junction

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Posted by dbduck on Tuesday, February 28, 2023 4:24 AM

richhotrain

The problem with manual switches is that you have to remember which way the reversing section is set ele

The OP is looking for a solution to remind him at all times how the reversing section is set electrically by setting up a system of trackside signals.

Rich

 

if the reversing loop points A & B are on the same turnout you can make a drawing of the turn out on your facia board or control panel, where the manual reversing switch is located, and put the switch between the two legs of the turnout drawing and The physical position of the reversing switch would correspond to which leg of the turnout. It needs to be aligned to

Another option. If you're using a tortoise switch machine on the turn out is to use a four pole, double throw switch, using two poles to operate the turnout machine, and the other two poles to change the phasing of the reversing loop, so that once the train has entered the loop when you throw the switch for the turn out, you're also changing the phasing on the reversing loop at the same time. This Will always ensure that the loop is lined up to the correct leg of the turnout

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Posted by richhotrain on Tuesday, February 28, 2023 4:35 AM

dbduck

if the reversing loop pointa A & B are on the same turnout you can make a drawing of the turn out on your facia board our control panel, where the manual reversing switch is located, and put the switch between the two legs of the turnout, and The physical position of the reversing switch would correspond to which leg of the turnout. It needs to be aligned to

Another option. If you're using a tortoise switch machine on the turn out is to use a four pole, double throw switch, using two poles to operate the turnout machine, and the other two poles to change the phasing of the reversing loop, so that once the train has entered the loop when you throw the switch for the turn out, you're also changing the phasing on the reversing loop at the same time. This Will always ensure that the loop is lined up to the correct leg of the turnout

Agreed. In the classic reverse loop, it is quite easy to visually determine phase. However, in some of the more complex reversing sections, it is not so easy to visualy determine phase. Trackside signals are still useful, but auto-reversers are superior.
 
Rich

Alton Junction

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Posted by wvgca on Tuesday, February 28, 2023 8:00 AM

with a manual toggle switch it's relatively easy to determine which way the phase is .. when the switch in the left hand position , the phasing should match what is coming into the reversing section from the left hand side 'normal' trackage ,,

it's only a saving of maybe 30 to 40 dollars, and is by no means 'automatic'

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