12 VOLT BAYONET BASE LAMP QUESTIONS

[JayOcks]

I was wondering if anybody could tell me the size of these bulbs in inches, mm, or or the standard light bulb size classification.
Also, what size socket works with them and if anyone could point me in the direction of finding sockets for these bulbs.
Thanks.

[Joe Satnik]

Dear Jay,

I'm pretty sure you are talking about a #53 lamp, (Radio Shack 272-1117) CM figure "F" below.

http://www.mouser.com/catalog/catalogUSD/641/114.pdf

It's possible this would work for you. (Mini-bayonet base, holder or socket?)

http://www.radioshack.com/product/index.jsp?productId=2062369

Hope this helps.

Sincerely,

Joe Satnik

[phillyreading]

The Radio Shack light bulbs come in either 14.4 volt or 18.4 volt in the bayonette style for that size.
Don't use automotive bulbs as they are rated for 12 volt DC.
You can use less voltage to make a bulb dimmer but don't go over the voltage rating as that will shorten the life of the bulb.

Lee F.

[Joe Satnik]

#53 lamp is standard for Williams and WBB.

[JayOcks]

Thanks for the info guys. If WBB uses the #53 bulb, why do they list it as 12v whereas the Chicago Miniature catalogue lists them as being 14.4v? Not a big deal, just curious.

[Joe Satnik]

Dear JayOcks,

It has to do with automobile lead-acid batteries which are nominally 12V. 

The charging system voltage regulator takes the battery up to 13.9V, perhaps even higher in colder weather.

Also, to charge a battery up in a reasonable amount of time, your regulator has to be set a bit above the target full voltage.

If your battery is disconnected while the engine is operating, the charging system can spike the voltage up even higher. 

In the end, the 14.4 V spec is a safety margin to keep from burning out the lamps in your "12V" automobile.

Hope this helps. 

Sincerely,

Joe Satnik

   

[phillyreading]

Joe,

For your info an auto's regulator will normally charge in the 13.4 volt to 14.9 volt range and be considered perfectly safe for automotive work, sometimes due to an extreme load on the alternator it could be as low as 13.2 volts. New car batteries should be 12.6 volts when fully charged.
Most 12 volt bulbs can handle 18 volts for short periods of time.
A lower volt bulb will heat up faster than a higher volt bulb and can melt some softer plastics.

Lee F.

[DominicMazoch]

I think th eShack also has 24 V bulbs.  But they would be dull.

[Joe Satnik]

Dear All,

Well, I'd guess that 18 Volt lamps would be dull, as the traditional power Williams/WBB locos fly around the track at pretty low voltages (hence the 14.4 Volt lamps, not the 20 Volts max of a Lionel traditional transformer). 

You'd probably have a hard time seeing the glow of a 24 Volt bulb at normal speed.   

One way to brighten the lamps up would be to wire the loco's dual motors in series instead of parallel. 

Two more advantages of series wired motors:

1.) Better control at low speeds,

2.) More power, less distortion for the True-Blast II sound system.

Hope this helps.

Sincerely,

Joe Satnik     

[JayOcks]

You've all been very helpful.
One last question:
Anyone know how or why WBB is able to charge around $15 for 50 of the bulbs when the Chicago miniature bulbs are .67 when you're buying 100 or more?
Not complaining, but this is a great price, I haven't been able to find miniature bulbs anywhere else at this price.

[Joe Satnik]

Old stock, haven't upped the price yet?

Overstock, want to reduce inventory?

[phillyreading]

Another thing about using 24 volt bulbs is that it may slow down your engine's top speed, as it uses more power to light up.
An 18 volt bulb should be the highest volt bulb to use with any O gauge train.

J O, the prices for light bulbs could be old stock left over from Williams. That's a very good price, but who needs 50 light bulbs?

Lee F.

[Joe Satnik]

Lee,

Power = Volts x Amps

Look at the specs for each lamp, compare power (VxA) and candlepower.  They should be proportional. 

The 24 volt lamp draws half the amps for the same power 12V lamp.

Hope this helps.

Sincerely,

Joe Satnik

[phillyreading]

Joe,

I think that you are mistaken on the 24 volt bulbs drawing half the power.
A 24 volt bulb will actually draw more power(watts) because the resistance is higher.

Lee F.

[Joe Satnik]

Dear Lee,

Ohms law: (V is voltage in "Volts", I is current in "Amperes" or "Amps", R is resistance in "Ohms", P is electrical power in "Watts".)

V/R = I

I x R = V

V/I = R

P = V x I

P = V x V/R (or V squared/R)

P = I x I x R or I squared x R

Same power with twice the voltage needs half the current.   

Your homework assignment: What happens to the resistance (of the lamp filament) in this case?   

Hope this helps. 

Sincerely,

Joe Satnik