Author Topic: Newbie Module Install #1  (Read 129 times)

LVRR1856

  • Fireman
  • **
  • Posts: 22
Newbie Module Install #1
« on: August 06, 2025, 10:10:10 PM »
Hey all,
Taking the first step and installing my first module. LM3-s into a P2k GP-18, going to try the 8 pin to 9 pin plug out.
I have some milling of the weight to make room, no problem, probably will with most installs ...

Reading some older posts, some guys left the Incandescent bulbs in, others added LEDs.
I'd like to keep the Incand. Bulbs at first, easy to change out later, assume they will work at 5v from what I understand is the voltage putout of the modules.
Question is .... is this a fact? Incand will work? , no resistors needed ? or just bite bullet and do LEDs ?

If LEDs ... question is ...
The ones I have have the preinstalled resistor on the positive wire, LM3s diagrams show it on the neg side ... does it matter ?

Figured I'd start a fresh thread on this. Thanks

G8B4Life

  • Signalman (Global Mod)
  • Conductor
  • *****
  • Posts: 1289
  • I'll think of a catchy tag line one day
Re: Newbie Module Install #1
« Reply #1 on: August 07, 2025, 09:03:48 PM »
...I'd like to keep the Incand. Bulbs at first, easy to change out later, assume they will work at 5v from what I understand is the voltage putout of the modules.
Question is .... is this a fact? Incand will work? , no resistors needed ? or just bite bullet and do LEDs ?

This is incorrect. The output of the LM-3S outputs is slightly less than track voltage, so almost 14v. I don't know what rating of the bulbs used in P2K locomotives was but if they are 12v then your likely fine (just turn the brightness down to essentially lower the output voltage). If the bulbs are 1.5 or 3v etc then you'll need to appropriately lower the voltage with external components, or just replace with LEDs and resistors anyway..

- Tim