MTH Proto-Sound P-2b Headlight Voltage

If this is true from the manual, they're 6V, that's the MTH standard for the CV boards.

The P-2 Box Cab locomotive’s headlights are controlled by constant voltage circuits inside the locomotive body.

Awesome!  Thanks for the info...

May I feed that constant voltage circuit using the 12VAC off the UCUB directly?

thanks!

-Mario

I don't know if that unit has the directional lighting that was triggered from the 1.5V outputs of the PS/1 board, so I can't say for sure that you can drive them that simply.  Although this if for a different engine, some models had a fairly fancy lighting board that switches the 6V lighting using the 1.5V outputs.  Here's one, I believe this came from an F-unit if I recall correctly.  You have to actually see what they're plugged into.

Many locomotive with the CV board have this board, that you could power from the TMCC headlight circuit.

Update...

I don’t see a separate CV board in the shell. 

just the connections (front headlight are the blue wires and the rear are green) on the PS1 board.

What do you think I should use for voltage to the headlights?

thanks!

-Mario

In that case, they're 1.5V bulbs, that's what comes out of those PS/1 lighting connectors.

Thanks John!

I just swapped out the jumpers for AC motors and added the bridge for DC motors...

thanks!

-Mario

Jumpers for AC motors?  I never heard of a PS/1 board running AC motors.

gunrunnerjohn posted:

Jumpers for AC motors?  I never heard of a PS/1 board running AC motors.

The UCUB board was for AC motors...

The UCUB board was not PS/1 either, it's a TMCC add-on by TAS.   The UCUB does provide the same 1.5V for the lights on those two connectors as the original PS/1 board.

The documentation for the UCUB and UCUB2 is in the TMCC/LEGACY REFERENCE MATERIALS & MANUALS thread.

gunrunnerjohn posted:

The UCUB board was not PS/1 either, it's a TMCC add-on by TAS.   The UCUB does provide the same 1.5V for the lights on those two connectors as the original PS/1 board.

The documentation for the UCUB and UCUB2 is in the TMCC/LEGACY REFERENCE MATERIALS & MANUALS thread.

I think the UCUB II puts out 1.5V for the lights per the PS1; the UCUB instructions under the “Special Lighting” instructions, the output of the headlight circuits say 12V. 

thanks!

-Mario

I was looking at the UCUB2.  Yes, the UCUB puts out half-wave track power direct from the R2LC, so it's lighting requirements are the same as any other TMCC locomotive.  The UCUB also probably doesn't have those 1.5V connectors.

gunrunnerjohn posted:

I was looking at the UCUB2.  Yes, the UCUB puts out half-wave track power direct from the R2LC, so it's lighting requirements are the same as any other TMCC locomotive.  The UCUB also probably doesn't have those 1.5V connectors.

I still have a few of your LED lighting boards left and the Yelo-Glo LEDs; maybe I’ll try those!

Truthfully, I'd just stick a 470 ohm resistor in series with the LED, that's how I do LED headlights.

Note that you will have to add the .01uf capacitor directly across the lighting output to trigger the triac with just an LED load.

gunrunnerjohn posted:

Truthfully, I'd just stick a 470 ohm resistor in series with the LED, that's how I do LED headlights.

Note that you will have to add the .01uf capacitor directly across the lighting output to trigger the triac with just an LED load.

What resistor do I use to keep the 1.5v GoW bulb?

I'd have to know the current draw of the 1.5V bulb to compute that.

gunrunnerjohn posted:

I'd have to know the current draw of the 1.5V bulb to compute that.

John,

I’m assuming these are the voltage regulators for the cab lights that runs off track power... can I use this regulator for my headlights and feed it off the UCUB feeds for the front and rear headlights?

thanks!

-Mario

I doubt the cab lights are also 1.5V bulbs.  If you want to power the 1.5V bulbs, they consume 40ma at 1.5 volts.  So, to power them from the UCAB TMCC outputs, you'll need a 300 ohm 1 watt resistor.  The actual power dissipation in the resistor is .48 watts, and you'll want the rating to be at least double the actual power dissipation.

gunrunnerjohn posted:

I doubt the cab lights are also 1.5V bulbs.  If you want to power the 1.5V bulbs, they consume 40ma at 1.5 volts.  So, to power them from the UCAB TMCC outputs, you'll need a 300 ohm 1 watt resistor.  The actual power dissipation in the resistor is .48 watts, and you'll want the rating to be at least double the actual power dissipation.

Right. Cab lights measure 6v when lit. 

I presume you want to run the headlights from the directional outputs of the UCUB, right?

gunrunnerjohn posted:

I presume you want to run the headlights from the directional outputs of the UCUB, right?

Aye. Yes. I’ll order some 300ohm 1W resistors.