Common street lamps or other bulbs: does it matter if you use DC or AC?

Incandescent bulbs will work on AC or DC. No reason that I know of that you can't do this.

Just be careful you don't turn the voltage up to high or you'll blow the bulbs.

If you have AC, the addition of a diode in one side of the line to the lamps will increase life a great amount.  I did this to a 70 year old set of 14VAC Christmas lights where there are 8 in series for  a 112 volt circuit in the days of 110VAC at the outlet, and none of them have burned out yet.  A 50-100 volt diode at a couple amps should do the trick for most setups.  Draw more current, then get a higher amp rated diode.

And....if you are using accessories like the Lionel (or anyone's) Gateman, crossing gate or similar, if you use a DC transformer to power them, you eliminate that distracting A/C hum that one gets when they activate. Problem is, most DC train transformers from HO and race car sets, are 15 to 18 volts, but low amperage.

Thus, it often takes a transformer per gate to activate the item. I tried hooking up two older crossing gates to one transformer the other night, and it got two gates less than halfway down.

I have read on here of some people using the outdoor lighting transformers sold at box stores and the like instead of older DC train items. I can't speak for those. Another plus is no worry about phasing.

Greg

@Super'O' man posted:

I was curious, so I was thinking of using a simple transformer for street illumination or other items that just have bulbs in them. You can find inexpensive DC transformers at shows, so I thought this would work. thanks

Incandescent bulbs are easy-peasy and agnostic when it comes to power, and easy to tell when something's not right. After all, such bulbs are basically just a heated wire encased in glass, with enough heating lag time that concepts like peak voltage and spikes are basically a non-issue. Any voltage or waveform that results in a satisfactory 'old-school' glow will work just fine. My home layout has a gallimaufry of salvaged power supplies distributed under the top.

Accessories may be another story. On the simple end, solenoid-powered devices (like old-school crossing gates) may have some issues with permanently magnetizing the iron slug when used with DC (running again on AC will reverse the effect), and many accessories require DC at specific voltages to properly power the device. Such devices can be permanently and terminally affected if you stray too far afield!

For such devices, I've found inexpensive buck converters (which can accept 10-35 volts AC or DC and output a regulated and adjustable DC voltage) very handy for grabbing whatever voltage is handy and adapting it to fit the need. For example, my recent animated bascule bridge project ended up using three such buck converters, one each to power the lift section gear motors (at 6 VDC), the many LEDs (at just under 3 VDC), and the two Tortoise switch machines powering the traffic control gates at each end (at 9 VDC). All three are powered with accessory voltage (roughly 14 VAC) from the same source.

In any event, good luck!