I hooked up the building lights on my new DCC layout yesterday and have a problem. There are about 35 bulbs (Busch 4280 14-16V building lights) hooked to two toggle switches (about half on each) and when I turn them both on the lights dim (from what they were with just one on). I have both switches connected to one 12 VDC 1000 mA AC Adapter. Initially, I had them connected to one 12 VDC 500mA adapter and the dimming was much more severe. I’m not sure how many amps the bulb draws but it must be more than I thought. What’s the best way to fix this? I suppose I could just add another adapter and split the usage or would going to one larger, maybe 13.5 or 18 VDC? (I found a 13.5 VDC 1700 mA adapter at Parts Express). I would prefer stay with one adapter. Need some advice! (Note: I have 30 Model Power street lamps hooked to one 12 VDC 1000 mA adapter with no problems. I think they are 30 mA bulbs).
Being that I have a second hobby as a computer tech, the problem I had (same one you have, power supply not stout enough) was easily solved. I was using several old trainset power packs to run my lights and it just wasn’t working the way I wanted. I then struck upon the idea of using an old computer power supply. I dug one out of my pile of parts and hooked it up and turned it on. I then turned the structure lights on one bank at a time. The lights would dim for just a split second as the new load came on and then go back to their former brightness. I turned all the lights on and the lights all burned at the brightness they were supposed to have. Right now I don’t have many lights on the layout, being that I’m rebuilding it. On the old layout I had around 35 structures with 2 lights in each structure. That’s around 70 bulbs and the old computer supply was pulling them all with NO problem. It doesn’t take a big one either. The one I’m using is from an old 486 and is rated at about 180 watts.
If you’re happy with the appearance of the lights at 12 volts, I’d stick with that. Running the bulbs at or near their “rated” voltage will cause them to burn out much more quickly. I’ve got some 12-volt street lights that I run at 10 volts, and they’re bright enough for me.
You probably just need to split things up more. If you go through the math on the Model Power streetlights, 30 bulbs x 30 mA comes out 900 mA, just under the rating for that unit. I suspect the Busch bulbs are drawing a bit more than that, and you’ve got a few more bulbs as well.
I find interior lights, streetlights etc. are better if they’re run at about half- to three-quarters- power. Otherwise to me on full 12V they look way to bright and sort of toy-like. I hook mine up to old power packs with variable control.
Plus it makes the bulbs last longer, IIRC running a 12v bulb at half-power makes it last 4 times longer.
My first thought was a bigger power supply, that would do the trick, then I thought what size wire are you running. Most of us tend to to run small wire for our accessory wiring (phone wire and such). We forget that as the current draw goes up on this small wire the resistance of the wire goes up also. The problem could be in part due to small wire as well as an under rated power supply. If it were me I would find a power supply of at least 1 or 2 amps and run # 16 or #14 wire as feeder to the small guage lamp wire, there will be more lighting down the road.
Did a little more homework and the Busch bulbs are 45mA which is quite a bit more than I thought they were. I think I’ll just add another adapter and split the load.