Well, up to now, I've only been replacing Athearn Genesis micro-bulbs with
> 12volters, but now I want to try adding resistance to the original
> micro-bulbs. A resistor calculator I downloaded suggests a range of 575-800
> ohms, figuring 12v input and 15-20ma. Just wanted to make sure this
> calculator is working correctly - can anyone tell me if this is a good range
> to work with?
Close - you've divided 12 volts by .015 amps whereas you should be dividing (12
- 1.5v) by .015 amps = 700 ohms.
By my calc you need a 525ohm by 1/4watt for a 1.5volt 20ma or as Greg Proctor said a 700ohm (1/4watt) for the 1.5volt 15ma
Nigel
Actually, it wasn't me - it was the Windows-based program I'm using where I plugged in these settings. Regardless, 700 ohms is certainly in the range!
See, the things is that Athearn states the range of 15-20ma - they're no more specific than that. Which should I go with? I appreciate brightness over longevity, by the way...
Windows? It must be right! 8^P
In that case, don't fit a resistor! ;-)
Otherwise, buy a few resistors of different values between 470 and 700 ohms and experiment.
Have you tried this one?
"
Yes, but I prefer the stand-alone application - it just seems a lot easier.
In Athearn Genesis F units, it isn't easy getting a larger bulb to work. You may have to build an entirely new housing for it, and then you stand the risk of overheating the cavity and damaging the lens. That's why I want to give adding resistors to the original bulbs a shot.
The bulbs I'm talking about are Circuitron "Mitey Lites" which are 1.4mm and
1.5v which is pretty much the same as Athearn's bulbs. Heat generated by these bulbs is virtually undetectable -- unlike 12v bulbs -- the ones I have used don't get hot. Circuitron also sells the dropping resistors for these bulbs. I've installed these lights in Genesis F units with no problem but I run them on DC with a constant lighting so I don't know how much heat those resistors might generate. But, with the right combination of resistors you can get around that problem if there is enough room for them. Also, it seems to me that I have seen some DCC units that provide 1.5v source for lighting -- don't know what they were though.Jim Bright
Gregory Procter wrote in news: snipped-for-privacy@ihug.co.nz:
I tried an Athern Genesis F3 with a 470 ohm resistor in the circuit. The headlight was very bright for about 15 seconds. Then it burned out and had to be replaced. I would try at least a 560 ohm. Of course, my local Radio Shack only stocks 470 and
1000 ohm, 1/4 watt resistors and nothing in between. I put a 1000 ohm in the circuit and find that works fairly well, but the bulb is a tad dim.I went to my local Radio Shack and bought a package of 680 ohm 1/2 watt resistors - they work very good with the Athearn Genesis lamps.....p/n 271-1117.
Jim Bernier
"Woodard R. Spr> Gregory Procter wrote in
Try
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