# Accucraft Whitcomb bulb voltage?



## San Juan (Jan 3, 2008)

Does anyone know what the volt rating is on the Accucraft Whitcomb industrial switcher bulbs?












I tested mine with some batteries and 1.5v is not enough, 3v was still weak, and a quick test with 9v seemed too bright. At 9v I think it was almost enough to blow it. I couldn't find any documentation on what bulb is used on these.


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## Greg Elmassian (Jan 3, 2008)

Many Accucraft locos have a 6v regulator inside, my 0-6-0 and my K4 both do. Also, are they indeed bulbs or LEDs? My locos have a mix. 

Regards, Greg


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## San Juan (Jan 3, 2008)

They are bulbs.

6v sounds right on the money based on my battery tests. 


The battery I'm using with this loco for power is a 14.8v Lithium Ion. Just trying to figure out the right resistor to use. Looking to run the bulbs around 4 volts or so.


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## East Broad Top (Dec 29, 2007)

If they were regulated to 6 volts to begin with (which I'd assume to be the case given that the loco is track-powered out of the box), why not just keep the regulator in place and feed the battery output to the regulator (track) inputs? 

Later, 

K


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## San Juan (Jan 3, 2008)

I took the regulator out.

I used an LED resistor calculator and came up with around a 390 resistor. But not knowing the milliamps on this bulb my numbers could be off.


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## East Broad Top (Dec 29, 2007)

You can't use an LED calculator to arrive at resistor values for bulbs. They're two very different animals. You want a 5-volt voltage regulator for this. Radio Shack sells 'em for $2.00. You can buy 'em online for much cheaper, but it'll cost you $5 to ship. You attach the battery voltage to the V-in and ground, then you connect the light bulb to the V-out and ground. No resistors, no other components. You'll probably want to attach the heat sink to the frame of the switcher, but since it's metal, that shouldn't be difficult. Depending on current draw, you probably wouldn't even need to do that (many manufacturers don't), but since you've got a metal frame, why not take advantage of it? 

Later, 

K


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## TonyWalsham (Jan 2, 2008)

The only problem attaching the regulator to the frame is the tab has a ground potential which means the frame would then have a ground potential. That could be a problem if the frame ever came in contact with a positive voltage. 
My advice would be to use a mica insulator and plastic washers with a screw and nut holding them in place.


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## Dan Pierce (Jan 2, 2008)

For battery operation, just replace the bulbs with leds. Less current, less heat, no regulator needed, just a dropping resistor. 680 ohm dropping resistor for 14.8 volts gives less than 20 ma for the led.


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## Greg Elmassian (Jan 3, 2008)

Just guessing, but it can be a pain to replace bulbs in some of the small headlamps. I have been in the same situation with some Accucraft and Berlyn models. 

Greg


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## San Juan (Jan 3, 2008)

*Update*

I finished the battery/RC conversion. The Accucraft Whitcomb is an incredibly smooth running loco now that it doesn't have to get power via the rails. This was the last non battery powered loco on our roster. So I guess we are fully battery operated now.


My set up for this train is as follows. 
Three Bachmann side dump ore cars and the Whitcomb loco. The first two ore cars contain the Battery/RC components. The first ore car has an Airwire G2 board and a Phoenix 2k2 sound board, which includes the Phoenix computer interface jack. The second ore car has the battery (14.8 volt LithiumIon), on/off switch, and charging jack. All the ore cars have scratch built removable plastic load covers to hide the Battery/RC equipment. The third ore car has a plastic cover as well just to keep the loads uniform looking. When I get to Colorado, where our outdoor layout is, I'll glue on the mine ore loads to the plastic covers. I'll probably paint the plastic covers black before I put the ore loads on.


The speaker is under the loco cab roof. I used a bass reflex speaker that I typically use for HO DCC/sound (if they fit in the locos) and it worked great for this small G scale loco. I used varying size connectors between the loco and cars, with the larger sized ones used for the battery and motor leads.


Here's what it looks like:






























As for the bulbs, I ended up using a 290 ohm 1/2 watt resistor. Works great. Just the right headlight and backup light intensity. Doesn't get hot either as I wondered if I should bump it up and go with a 1 watt resistor instead. But so far it has been fine.


Oops, looks like I still have to paint the engineer


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## San Juan (Jan 3, 2008)

Here is the mine train with ore loads on our layout:


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