Massoth decoder: front and rear lights

idlemarvel

idlemarvel

Neither idle nor a marvel
13 Jul 2015
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I want to have the option to have both front and rear lights on at the same time, as in shunting mode.
Using a Massoth XL as an example in the diagram below, how should I wire it up so that if F1 is pressed (which turns on A1 output by default) that will turn on both front and rear lights? I know that front lights are connected to LI-V and +24v and rear LI-H and +24v, with the actual voltage to the lights (if not full track voltage) adjusted according to needs using CV settings.
I feel like I should be able to just connect A1 to LI-V and LI-H but I'm concerned I will short something inside the decoder if I do that. Help please.

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PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
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Tamworth, Staffs.
All the lights are connected to the +24v as a common supply, and you are switching the negative 'ground' connection, so you can do as you suggest..

I have used this to allow day and night running, on certain models, where a light is brighter running in daylight, than in darkness.

Just make sure, if necessary, you have set the voltage correctly on all the function / lighting outputs you are using.

PhilP.
 
dunnyrail

dunnyrail

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25 Oct 2009
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All the lights are connected to the +24v as a common supply, and you are switching the negative 'ground' connection, so you can do as you suggest..

I have used this to allow day and night running, on certain models, where a light is brighter running in daylight, than in darkness.

Just make sure, if necessary, you have set the voltage correctly on all the function / lighting outputs you are using.

PhilP.
As Phillip warns ensure that the Voltage is correct for your chosen Lights. The default setting when you buy the decoder is the full 24v so you need to change the relevant CV before you try the lights.
 
idlemarvel

idlemarvel

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13 Jul 2015
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Thanks PhilP and JonD, just what I wanted to know.
 
ntpntpntp

ntpntpntp

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If you're going to connect both light to A1 as well as leaving them connected to LI-V or LI-H, you'll need to make those extra connections using diodes otherwise both lights will also light when LI-V or LI-H is on.

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idlemarvel

idlemarvel

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13 Jul 2015
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Hmmm, good point ntpntpntp ntpntpntp thanks
 
J

John S

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Moved
 
Last edited:
idlemarvel

idlemarvel

Neither idle nor a marvel
13 Jul 2015
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Ascot
Thanks JohnS. I think I prefer the earlier solutions as they minimize wiring. If I use A1 as an additional output for forward lights and A2 for rear lights, and have them both triggered by the same function key, then I won't need any diodes. Bit wasteful of outputs but there are plenty on an XL.
 
D

Dan

Registered
28 Jan 2010
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Eastern MA
I would just set CV51 and CV52 to 192. Now you can turn lights on and off with F0, but both front and rear will be on with no parts added.
 
PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
24,387
831
Tamworth, Staffs.
I would just set CV51 and CV52 to 192. Now you can turn lights on and off with F0, but both front and rear will be on with no parts added.
Dan,
Line one, post one:

I want to have the option to have both front and rear lights on at the same time, as in shunting mode.
So, not both on all the time..
 
idlemarvel

idlemarvel

Neither idle nor a marvel
13 Jul 2015
1,880
178
Ascot
Just to close this off, on the XL decoder I connected A1 to LI-H (rear lights) and A2 to LI-V (front lights) and set the A1 and A2 outputs to 5v and to be triggered by the same function key, F8 in my case, which also sets shunting speed. So F0 sets the lights on according to direction, F8 switches both front and rear lights on, which is what I wanted. Incidentally the LI-I (internal lights) connection comes on as well if A1/A2 are triggered when they are hard wired to LI-H and LI-V.