Not knowing much about electricity and having used LEDs everywhere else, I now have an older signal that uses incandescent bulbs that I would like to install.
The instructions call for 12 to 16 V and 3 amps, saying this is best to give best bulb life. Will lesser power, say 9 v 1.5 amp, shorten bulb life or not? Seems the bulb is bright enough for my purposes with the 9 v supply.
Thanks
It won’t hurt the bulbs a bit. In fact, lower voltage will make them last longer, though they will not be as bright.
Yes, the lower voltage will generally extend the bulb life. Amperage shouldn’t be a concern, AS LONG as there’s enough available amps to run all the bulbs, and you are not drawing more amps elsewhere in the circuit.
In other words, if you have a 12 volt bulb, and a motor wired in series, and provide 12 volts, the bulb will (in theory) draw 6 volts, and the motor use 6 volts. The difference is, the bulb may draw 1/4 amp, the motor might draw 1 amp (or try to). Now let’s say you wire them in parallel. Both will get 12 volts.
If the bulbs use 1/4 amp at 12 volts, you’ll need a minimum 1.5 amps to run 6 bulbs at a time. Chances are the bulbs will use closer to 1/10 amp, or 100 milliamps, each.
Brad
Rough rule of thumb I noticed is that by lowering the voltage 10%, 12V->10.8V, you increase bulb life 30%. This all depends on the bulb construction though.
Actually, series wiring will only work as described if the resistance of the bulb and motor are the same. In series wiring, all devices in series will draw the same current, although the voltage each of them gets may be different.
Parallel wiring is as described, assuming the power supply is sufficient to power everything.
Yeah … what he said. Mine was more of an example than anything.
Brad