I added on to my diesel shop and I am getting ready to wire it up. The meager instruction sheet only mentions that it can be powered by ac or dc power up to 12v. I am planning to power it from the same decoder that runs my turntable motor, but need to know the resistor value to drop the voltage to below 12v. Without the lamp specs I can't calculate the resistor. I don't have a multimeter to measure it directly. Does anyone know the appropriate amperage for this lamp? Thanks in advance. Richard
The best advice I can give is "Go to Harbor Freight and buy a meter."
These small bulbs typically need about 30-40 milliamps. I would probably run them at 9v to save bulb life and dim them down a bit.
It takes an iron man to play with a toy iron horse.
I just measured the one spare 2310 lamp I have.
12VDC = 24 mA The lamp is fairly dim at this voltage. Probably last much longer, though.
I did check at 14VDC and got 27 mA using a lab power supply.
Hope that helps, Ed
Thanks to both of you for your assistance !
Just to put a ribbon on the topic, here is the official reply from Walther's customer Service:
'Good Morning Richard, The new number for the item you have is 949-4319; same set of lights, new number. Each bulb draws 25mA @12volts. Regards, Gregg Volke Walthers Parts & Warranty"
Thanks again to those that chimed in.
Another approach is to guess very low on the current (high on the resistor) and swap in lower resistance values until you're pleased with the output and it's obviously not burning super bright. That only works if you've got a stash of resistors around, though.
But I second buying a meter. I don't know how you can be in this hobby without one. Even the inexpensive ones are as good or better than a lab meter from years ago - for $10!
Use a couple of diodes. They are cheap and each one drops the voltage 0.7V->1.0V (typical). This is specified as the forward voltage (Vf) on most spec sheets.So if you put 3 in a series you have a gaurenteed 2.1V drop. 12 - 2.1 = 9.9Vhttps://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/introduction-to-diodes-and-rectifiers/
Don - Specializing in layout DC->DCC conversions
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