Bulb voltage as fitted to Proto 2000 "PA" diesel

[Fred M]

G'day All,

Just wondering if some of you blokes would know the voltage of the bulbs used in the Proto 2000 "PA" diesel, the instructions tell me to replace the bulbs with 12 volt bulbs when changing to DCC.

I intend to install a couple of resistors in line for the head light and Mars light, and to do this I need the bulb voltage, so if some one can help.

Much appreciated

PS
Sorry Mr. Bach-mann for placing this on your forum site, but thought this would be alright as I do have a lot of Spectrum Steam Locos

[Rich R]

Hi Fred,

Can you get to the bulb and the wires easily enough? Use a 1.5 volt battery to test the headlamp. If it lights you ain't runnin' 12 volts. If it barely glows or doesn't light at all then you've more than likely got 12v plus.

But then again you know that don't you........   

Cheers mate,
Rich R

[Jim Banner]

To properly size the resistors, you need to know both the bulb voltage and current.  You also need to know what voltage your decoders put out to the headlights etc. when running on the DCC system that you use.

Here is what you need to do.  First figure out the necessary voltage drop.  This is the difference between what comes out of the decoder and what goes into the light.  For example, if you get 14 volts out of the decoder and the LL bulbs are 2.5 volts, the voltage drop is 14 - 2.5 = 11.5 volts.

To get the resistance, you divide the voltage drop by the current. Suppose the headlight bulb draws 60 milliamps (or .060 amps, which is the same thing.)  Then the resistance of the resistor is 11.5 volts / .060 amps = 19.17 ohms.  They do not make 19.17 ohm resistors but they do make 22 ohms, which is close enough.

But resistance is only one of the ratings of a resistor.  Another important rating is its power rating, that is, the amount of power it can dissipate without over heating.  The power in this case would be 11.5 volts x .06 amps = .69 watts.  A common 1/2 watt resistor would not last long and would run very hot.  A 1 watt resistor is bulky and might be hard to find room for.  An alternative would be to use two 10 ohm, 1/2 watt resistors in series.  In a series circuit, the resistances add together, giving 20 ohms (even closer to 19.17) and the power ratings add, giving 1 watt total.

Now, hopefully, someone will give you the voltage and current rating of those bulbs so that you can do the actual calculations.  Personally, I just toss them out and install warm white diodes and a 1000 ohm resistor.  The diodes only need 10 milliamps to operate and the resistor dissipates only .1 watt so heat is never a problem.

[Fred M]

Thanks Rich and Jim,

Rich, just goes to show how slow I can be, didn't even give that notion a thought,

Jim, will save your answer to my Folder for future reference.

Regards 

[Hunt]

The bulbs (technically lamp) are most likely 1.5 V and...  yes, you do need to replace with 12V per the instructions when using DCC or you will need to add resistor(s) to the light circuit.

You will get a better MARS light effect with a lamp than with a LED. There are special effects modules which can use LED for MARS light.

[Jim Banner]

Hunt is, of course, correct.  These things with tungsten filaments are "lamps."  Bulbs are what you plant in the ground.   I suspect the term "bulb" meaning lamp was a result of their bulbous shapes.  So why do so many people and stores insist of referring to compact fluorescent lamps as compact fluorescent bulbs?  Why not "worms" or "snakes?"  Beats me.

All that aside, if you call them "bulbs," I will not be thinking you are planting tulips in your locomotive (note: not your "engine," your "locomotive.") 

[Fred M]

Well blokes, I appreciate your concerns for me not using the correct term and calling a"lamp' a "bulb", In my country, my term is correct, a question for you Hunt, what do you call the main light on the front of a motor vehicle?, we class them as "headlamps" and on the rear of a vehicle, these are called "rear combination lamps" and both these items have "bulbs fitted to them.

You are right and so am I.

Regards   

[Rich R]

Hi Fred,

This is strange really isn't it? I mean I've always called those big bright things on the front end of my vehicles either headlights or head lamps. On the rear always tail lights. On motorcycles headlamp, headlight and passing lamps. Tail lights and stop/brake lights. Those directional things have always been turn signals or if you remember them, the Brit flipper things that stuck out from the top sides of the vehicle. Had a 48 Anglia and a 58 Hillman that had those.
English, weird language actually. Thomas Edison perfected the light- lamp?
It's a flash light not a flash lamp, It's a flash bulb not a flash light/lamp but it's still a torch in england.
As long as you get it to do what you want it to do then call it a bloody eggplant if you wish.
I'll email you later.

Cheers,
Rich.

[Atlantic Central]

If our good friends at Webster's are of any help in this matter, we might say that "electric light bulb" or even "light bulb" is a correct phrase but to just call it a "bulb" leaves one with doubt.

As a trained Electrician and Electrical Designer Draftsman, the replaceable part with the filiment is a lamp, the device it is in is a fixture or  a light, or "light fixture". Edison perfected the "electric light", the "electric light bulb", or even the "light bulb" but not the "bulb". So if you just say bulb how are we to be sure of what you speak?

On a similar note, that piece of equipment that heats your domestic water is a "water heater", not a "hot water heater", the only place "hot water heaters" are commonly found is inside dishwashers where already heated water is made hotter. And, concrete is "placed" not poured, since it is not technically a liquid at any point in the process.

Oh yes, two nations divided by a common language.

Sheldon

[Fred M]

My dictionary quotes "bulb" as being an INCANDESCANT Lamp

I have tried to attach the Walthers instruction sheet to this post, I don't think this was successful which will be disappointing.

You can place cement, Over here we will continue to pour cement.

Also I couldn't give two sucks of a sav for your criticisms.

If you couldn't understand my post, I'm really sorry you read it.

Now!! do you all think we can get back to my original post about "bulbs"

[Rich R]

Hi Fred,

Sure can! I've scanned an article that I want you read. It's something I found that just may solve your lamp voltage problem.
I'll fire it off in a few minutes.

Cheers mate,
Rich

[Fred M]

G'day Rich,

You realize that broadside wasn't fired at you, just that if I could have got that Walthers instruction scan to attach to this forum, the critics wpuld have seen that they were barking up the wrong tree, never mind though, it livens up the Forum somewhat

R'gards

[Rich R]

Hi Fred,

No worries mate! Which was better though? The jpeg or the RTF docs.

I mean which was easier to read  not which was better as I doubt there was much of real import in that. I really need to upgrade my OCR software.


Best,
Rich.

[Fred M]

G'day Rich,

Yeh!!, the second lot of scans that come through, were a lot easier to read, did you happen to browse the docs. before you emailed them, you would have noticed that part of the doc. referred to light bulb and then bulbs, I wonder if that was referring to onion/tulip or even lily bulbs, I guess I will have to read that doco a few more times and make sure I understand it, the Walthers instruction sheet is no different with their references to bulbs.

Sorry mate, for using you in this way, just had to have a last shot, maybe.

Best Regards

Fred

[r.cprmier]

Sheldon;
Uncle Noah also pronounces "forte" as (for-tay, as well as fort, thus weinieing out of a touchy subject).

My first job as an electrician was with what was probably (in my opinion) the biggest SOB I ever had the displeasure of meeting-but he did know his stuff, and I did learn rightfrom wrong with him.
To be sure, an electrical device intended for lighting is known as a "lamp". 
-To hell with the dictionary!!

RIch