Headlight dimmer option for an RMI?

[GO&PRR]

Good evening! Question for folks that have an RMI loco, is there a headlight dimmer that can retrofit into a controller Model 2020? The headlight is very bright and would be very gentlemanly to dim for oncoming traffic. Thanks for any input/ideas!

[Greg_Lewis]

While I don't know about the 2020 controller, you might be able to do it with a PWM dimmer. I've done that on my RMI gas hydraulic. The actual circuit board of the cheap PWM dimmers you can get off Ebay is very small. There are quite a variety on Ebay for as little as $5 with shipping from China. I've used a bunch of them for various projects and they have worked fine. I see one that is less than 1 inch in all directions.

[GO&PRR]

Thanks Greg. As the relays and power voltage are on the loco, thinking of replacing the two position switch on the control box with a three position version (off-dim-on) using a spare wire, will need to verify that there is a an unused pin first. Run this to a relay and the PWM you mentioned to the light circuit ground line. Note, the loco has the auto forward /reverse headlight relay thus thinking the using the common ground wire may be easier to do.
(if this was a steam circuit, would be easy. not real good with electrons. lol)

[Greg_Lewis]

If you don't have a spare wire in the cable, you could either replace the cable or piggyback a conductor onto it with cable ties or shrink wrap. But the idea of a relay sounds interesting. What about a sequencing relay? Then you would only need a single conductor to the relay plus the main ground. I would suspect there would be power to the control box which would give you the voltage to trip the relay. Each trip of the switch would kick the relay from bright to dim, with the main on/off light switch on the loco.

[GO&PRR]

Update - Called RMI and Bill pointed out they they have a retrofit kit for the early electric loco's. It can be found on their website by drilling down some. Sent a follow up email and waiting on a quote.