I have 18 volts of power for my acc line. I have some ho gauge street lighting that requires 2 volts.... I need to know what size resistor to put in the line to run the lights without blowing them up.. Thanks!
Original Post
Replies sorted oldest to newest
It depends on how many lights you have. If they are incandescent, measure the impedance with an multimeter. Say they are 100 ohms, you need a resistance, X, that is 2/18 of 100+X. Or 13 ohms. the current flow will be 18V/113 ohms = .16 amps, so there will be 2V x .16A = .32 watts dissipated in the resistor. Therefore you need a 13 ohm resistor with at least a 1/3 watt dissipation rating.
Are they incandescent bulbs? If so measure the resistance (ohms) across one. Multiply that number by 8 and wire the resistor in series with the bulb. Another option is to wire 9 of the lights in series with each other and not use a resistor. If you have a lot of lights to wire this may be the ticket. If one lamp burns out, the rest will go out though.
If they are LEDs, they likely require DC, and will need more than just a resistor to work.
Hope this helps,
J White
Ig they are LED's you'll have to worry about the max current thru them. They'll still work, but you'll see a flickering as they turn off 30 times per second. You could put two in parallel with each other at each desired location to eliminate this
Wire up a branch line, the full 18 volts to a small group of lighting that is always on when the 2 volt lamps are on that you want to power. Put in series 6 diodes,3 in one direction and 3 in the other direction with that line with one of the leads.
Diode assembly with 4 pair is shown here,but make yours up with 3 pair.
www.jcstudiosinc.com/BlogShowT...=488&categoryId=
Tap the leads at both ends of the diode string which is in series to the 18 volt lights. These 2 taps will yield 2 volts AC whenever current is pulled through it to light the 18 volt lights. The voltage to these lights will be reduced about 2 volts.
Dale H
I have some low voltage lights, LEDs actually. I use a battery box with a little switch on it. Also used the little chargers that plug in the wall. Have a bunch after all these years.
Originally Posted by Jim wendt:
I have 18 volts of power for my acc line. I have some ho gauge street lighting that requires 2 volts.... I need to know what size resistor to put in the line to run the lights without blowing them up.. Thanks!
I'd probably consider rolling my own power supply with a regulator. Using a resistor to drop that much voltage will require a sizable resistor and will also not supply as steady a voltage as an active regulator.
A diode, capacitor, two resistors, and an LM317T is all you need to do a regulated supply.
THANK YOU and all who have made suggestions! 
According to the instruction manual, this loco DOES, in fact, smoke better at higher voltages and with the heavy tender plus a train!
I should have my tender NLT Tuesday, and will couple a medium heavy freight train to test the smoke unit at 16 volts or higher! 
Originally Posted by Tinplate Art:
THANK YOU and all who have made suggestions! According to the instruction manual, this loco DOES, in fact, smoke better at higher voltages and with the heavy tender plus a train!
I should have my tender NLT Tuesday, and will couple a medium heavy freight train to test the smoke unit at 16 volts or higher!
I think you posted this to the wrong thread.
