Hi I am modeling steam in ho and dc. I would like to know if there is a way to make the headlight brighter without running wide open throttel. That is way to fast for the engineer to see down the track’s even with bright lite could not stop in time, going slower light is so dim he can’t see anything. Thank’s for any help. I am in the dark.
Larry
The problem with lighting using straight DC is that the bulb brightness is directly tied to the input voltage to the track & loco. When the throttle is low, the voltage is low and the bulb is dim.
There are constant voltage circuits available to correct this. They use low voltage bulbs and some sort of voltage regulator to maintain the low output voltage to the bulb even when the throttle is at a higher level.
I’ve seen articles in the model magazines over the years on these circuits. If you’re inclined to make your own, you might want to research thru the magazine article index search at-
I’m not sure if there are still commercially available circuits out there. Try a Googhle search.
Of course, with DCC, you get the constant brightness lighting automatically.
Doug
I’ve used 2 volt - 100 ma voltage regulators, Digi-Key Part # TK11620CT-ND when I operated with DC control. Unfortunatly that IC is no longer available. They do have a 1.5 volt. 1 amp regulator in a TO-220 case (larger than the TO-92).
Larry,
Are you contemplating DCC at some point? LED’s are a vast improvement over the 1.5v incondescent bulbs and put out a brighter, more prototypical light. As Doug alluded to, with DCC you have a constant voltage running though the track so your LED stays bright - weather you are in motion or at a dead stop. On DC, the voltage is regulated up or down by the power pack when you go faster or slower. LED’s are very “digital”: they are either on or off and need th constant voltage to light up. I’m running DCC and switched my headlights to LED’s a couple of months ago. Absolutely NO comparison…
Tom
Hi Larry,
Back in 1991 I authored an article in Model Railroader entitled “Diode Lighting Made Easy”. This article has since been reprinted and is included in the Kalmbach book “Realistic Animation, Lighting & Sound” which should be still available. If you are planning to stay with regular DC, diode lighting will give you the constant brightness headlight you desire. Of course, if you are planning to convert to DCC, the decoder will provide it for you.
Bill
Yes, with Digital Command Control (DCC) you get constant brightness headlights and you can make them be as bright as you like depending on the resistors you use when you install the decoder.
Here’s a sample of some nice, constant brightness headlights using DCC:
For a larger image, click here: http://mymemoirs.net/model-trains/forum/phpBB2/images/trains/LocoHeadlights.jpg
Wow - I think I need to put some sunglasses on. Nice!
Joe - that bridge looks identical to a bridge here in Ventura, CA (on what was of course, an SP line). Must be some sort of standard issue SP railroad bridge.
At a model railway expo down here in Australia last year, I saw someone who had combated your problem. DC steam (S Scale). He isolated the headlight from the actual motor. Then using standard AA or AAA batteries, made his own circut for the headlight which was mounted ontop of the motor. I thought it was very clever!! 
Thank’s all for the replies. I am staying with dc for now, can’t take the dcc plunge yet. Bill sounds like i might have to look for the book and see what i can do. Thank’s again.
Larry
I read an article about steam locomotive headlights in an old issue of Railroad Magizine.It said most steam locos only used headlights at night time.This was probably pre 1940.
Here’s a reversing constant intensity circuit available from Discount Internet Trains made by Miniatronics.
http://www.internettrains.com/minconligfor1.html