Model Railroading > Headlight Dimming Circuit

I am need of a headlight dimming circuit for my 1 1/2" locomotive. I am going to use one of those really high intensity lamps (12VDC) and need a circuit to use 12VDC for high and 6VDC for low. And due to space limitations, I can not use large 6 volt lantern batteries but rather two 9VDC batteries so I also need a suggestion as to how to low the voltage from 18VDC to 12VDC

Marty Harrison
Knob Noster, MO

perhaps this might be of some help or info. Doug
http://www.trevorheath.com/livesteaming/articles/brightdim.html

Double Throw-Double Pole toggle switch or a Rotary selector switch should do the job.

hoggerdoug Wrote:
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> perhaps this might be of some help or info. Doug
> http://www.trevorheath.com/livesteaming/articles/b
> rightdim.html


Would the circuit in the link work on 12 volts? My engine has plenty of space for a car battery.

If not, is it possible to get 24 volts by using two car batteries? I was never that good with circuits to begin with, and I'm little rusty, but I thought if they were wired in series it would double the voltage?



Edited 1 time(s). Last edit at 04/18/14 19:05 by pennsy3750.

Batteries in series produces a combined voltage, right?

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Marty Harrison
Knob Noster, MO

First, what is the wattage rating of the 12 volt bulb? Define the voltage source you have available: two 9 volt batteries or two 12 volt car batteries. Have you tried the bulb operating on 6 volts to know that is the brightness you desire?

Edit: yes, combining batteries in series will produce the sum of their voltage ratings. Current draw will be limited to the one with the lowest current rating.

Matthew



Edited 1 time(s). Last edit at 04/18/14 19:54 by jmprice.

I am planning to use a 12VDC track light that I picked up at Lowes and could use a single 6VDC battery for dim and two 6VDC batteries for high. Already managed a quick test of headlight--works great but I think the two 6VDC lantern batteries are too much to fit in cab of my engine. Have been looking at using two 9VDC batteries but need to drop the voltage to 12VDC.

mth

Marty Harrison
Knob Noster, MO

Two 9 volt batteries will probably not last long for that type of bulb, but I still don't know the wattage of the bulb. Can you answer this?

Matthew

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