Now that we have finished the tread on bulbs I have three more questions.
I have just puchased the Block Animator/2-SBCA from Logic Rail. The signal I am going to use have two targets on one stand. I am tying the Red leads together and the Greens together from each target so the reds and green from each target will turn at the same time. Hear is my questions.
How does what I described affect the voltage and or current to each bulb?
If it reduces the voltage would I then not use a resistor in the circuit?
Will this make any difference to the BA Board?
Harold
LEDs use to operate at ~1.4V and 10-20ma depending on the intensity of the LED requiring a 360 Ohm series resistor to limit the current to 10ma (half that or 180 for 20ma).
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but 5V is sufficient to to wire two LEDs in series so that they share a current of 10 ma with a 220 Ohm resistor
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greg - Philadelphia & Reading / Reading
There not LED's. They are incandesents. I am going to apply a 12v DC Reg power supply
then the question, again !, is what is the current rating of the bulbs and what amount of current can the circuit board supply without damage
?
These are old signals and are using two grain of wheat bulbs for the lights.
The new board takes 12vDC - to 17v AC. I know the bulbs can handle 12v. I was going to use a resistor just for luck.
My question is this.
If I hook the two reds and two green together from each target am I reducing the voltage and the brightness of the bulbs? My concern is if I still use a resistor the bulbs will be to dim.
Try it and see. If the voltage is reduced it won't hurt the bulbs.
Dave H. Painted side goes up. My website : wnbranch.com
Good advise. I hooked up a circuit on my bench. With either one or both wires connected the voltage was the same (12v). I put in a 220 ohm resistor and the voltage droped to 5.6v. I now know to settle on a 100ohm which should be just right.
When I started model railroading there were no LEDs yet, so my experience is still with incandescents. But, I did produce a signal bridge with LEDs. I got it to work, but I had one surprise.
I am used to wiring lights in parallel. When I did this with LEDs, particularly different color LEDs, they didn't work as intended. One bulb would work, but the other wouldn't. I realized that one bulb was taking all the current and starving the other. The solution was simple - wire in series, not parallel. That simple change made it work.
It takes an iron man to play with a toy iron horse.