I have a dual, red, LED crossbuck grade crossing signal (N.J. International #1090, 12-14 V). Four red wires leave the bottom of the signal base, none of which are labeled in anyway (anode, cathode, bulb one or bulb two). How can I test this signal to appropriately mark each lead? The package is labeled 12-14V. Does this mean the LED will light with 12 volts DC without a current limiting resister? I can't find any useful information on the company website.
Thanks in advance.
John
Although I don't have that specific item, and their web site is no help, I can offer some general troubleshooting techniques which should help you determine which wire is which.
Although the package labelling would tend to indicate that it would operate right off 12 volts, I can't see them stuffing a couple of resistors into the mast. But then, what do I know?
To be on the safe side, we'll assume that it has no resistors. Bring out a couple of wires from a 12 volt D.C. supply and put a resistor in the positive lead. Any value between 500 and 1,000 ohms will do. If there is a resistor there already, the LEDs will just be faint. Try every combination of pairs of wires with the 12 volt supply (and resistor) until one of the LEDs lights up. The wire that is connected to the positive wire of the power supply will be its anode. Now it's just a matter of which of the other two wires is the anode for the other LED. It does not hurt an LED to have the polarity of its voltage reversed. It just won't light up. If the LEDs are dim, then there is already a resistor in the mast. If you are uncertain about the brightness of the LED, measure the current it is drawing with your test setup. If there's two resistors in series (yours and theirs) the current will likely be less than 10 mA. If yours is the only resistor, it will be more than 10 mA depending on the size of the resistor you are using.
I hope this helps.
..... Bob
Beam me up, Scotty, there's no intelligent life down here. (Captain Kirk)
I reject your reality and substitute my own. (Adam Savage)
Resistance is not futile--it is voltage divided by current.
I doubt this is a "forum first," but I have solved my own problem.
I assumed that the "lights" in the crossbuck were LEDs and built my flashing circuit based on that fact. I just pulled the "lights" out and they are red, incandescent, grain-of-wheat bulbs, which explains the 12-14V label on the package and the fact that my circuit wouldn't work!
I'll replace the lamps with LEDs and be back in business. Sorry for the confusion.
http://www.njinternational.com/hoscale1.htm
Their web site clearly notes "Lit w/Bulbs"
MOAVBILLY http://www.njinternational.com/hoscale1.htm Their web site clearly notes "Lit w/Bulbs"
Strange, that's not the same page I got when I went to their web site. The page I got did not say "lit with bulbs." Oh well, the OP solved his problem and that's what matters.