Any electrical engineers in here??

[Docwheelhorse 2,687]

Hello All, 

So say work throws out 3 dozen Made In USA GE headlight bulbs that where spares for our long gone Emergency Lighting.

I took 'em... probably worthless-- then had a thought.

 

Is there or can I build some type of resistor to put in line at bulb to cut voltage from 12 to 6?

 

I dont care there only 12 watts.... i dont use headlights much anyways and these are just nice crystal clear USA bulbs.

 

Several of my tractors are Briggs units with the AC lighting that changes voltage with RPM too.

 

Thoughts?

 

Thanks

Tony

 

 

[lynnmor 7,512]

I guess you will be using 2 at a time, simply wire them in series.

[Docwheelhorse 2,687]

Explain? 2 in series will handle 12 volts? How do I do that and thanks!!

[davem1111 2,079]

11 minutes ago, Docwheelhorse said:

Explain? 2 in series will handle 12 volts? How do I do that and thanks!!

 

<---- Not an electrical engineer, but a computer guy and a tinkerer, sometimes with things that I shouldn't be tinkering with like 240v circuits 

 

I think what he's saying is, run the hot wire to the positive terminal on the first lamp, then run a wire from the negative on that to the positive on the second one, then attach ground to the negative terminal on the second one. 

 

I've used 12v batteries in parallel before, and knew that putting them in a series would double it to 24v, but never thought about using the consuming devices in a series.  Did I get it right? 

Edited February 25 by davem1111

[Docwheelhorse 2,687]

If its that easy you guys have put a big smile on my face!!

 

Tony

[Wayne0 764]

Yeah, that will work.

[Handy Don 13,139]

1 hour ago, Docwheelhorse said:

If its that easy you guys have put a big smile on my face!!

 

Tony

Excellent save!

The ONLY issue is that like those wired-in-series Christmas light strings, when one bulb burns out, both lights go off. Remember swapping a known good down the string until you got to the dead one? Same (but at least only two bulbs!)

[ri702bill 8,809]

5 minutes ago, Handy Don said:

The ONLY issue is that like those wired-in-series Christmas light strings, when one bulb burns out, both lights go off

East enough to check for voltage in & out of the first bulb.

[Handy Don 13,139]

Just now, ri702bill said:

East enough to check for voltage in & out of the first bulb.

Dark and got volts? This is the dead one.

Dark and no volts? This one is still good. (Unless BOTH lamps blew at the same time! )

 

No access to the connections on those pesky Christmas lights, though! 

[Ed Kennell 39,935]

I have repurposed 6V emergency lights on my snow machine.  They even come with an adjustable base.     It's actually easier to wire in series than in parallel.

 

 

 

.

[Docwheelhorse 2,687]

Thank you all!!! 

 

Tony

[Retired Wrencher 5,602]

12 hours ago, Docwheelhorse said:

If its that easy you guys have put a big smile on my face!!

 

Tony

Doesn’t Mike know how to do this Tony.

[Racinbob 11,569]

Yes, just a simple series circuit. The downside it what they said, one burns out they both go out. But a bulb operating at half voltage will last about a million years. 

 

[squonk 42,030]

Every time I see those old E light bulbs I think of the time I ran into a ghost one night when I was doing our annual 90 minute E light test! 

[Ed Kennell 39,935]

2 hours ago, Racinbob said:

But a bulb operating at half voltage will last about a million years

 

        

We don't often get to correct Bob.          Those 6v Emergency bulbs are seeing a full 6volts.         

 

[Racinbob 11,569]

11 minutes ago, Ed Kennell said:

        

We don't often get to correct Bob.          Those 6v Emergency bulbs are seeing a full 6volts.         

 

 

100% correct. Can I blame it on not having finished my first cup of coffee? 

 

I guess my mind went back to when, as a contractor, we were working in a very large orthopedic firm in Warsaw. At the time their main plant had a 14 acre footprint and was about 50% 2 levels. They had the type of emergency lights referred to here. You can imagine how many. Doing routine checks they would find several bulbs out. I tossed out the idea of wiring the bulbs in series. The downside was that they would likely come up short on the lumen output. But in reality I thought it would still be plenty. We experimented in one large office area. Even though the office workers were quick to complain they didn't even notice. 

Keep in mind here. That's 6v bulbs now operating at half voltage. The light output actually is cut to about 25% their normal doing that, not half like you might think. 

In Tonys case he'll have 6 volt bulbs operating on a 12v supply wired to supply........half voltage......which is.....................oh yea.......................6 volts. 

Tony, the good news is that it will work. The bad news is that when one burns out they both will be out.............and they won't last any longer. 

[953 nut 56,981]

1 hour ago, squonk said:

I ran into a ghost one night

[rjg854 11,748]

11 minutes ago, Racinbob said:

Tony, the good news is that it will work. The bad news is that when one burns out they both will be out.............and they won't last any longer.

I don't think that will matter to much seeing that box full of bulbs he has.

[Handy Don 13,139]

2 hours ago, squonk said:

Every time I see those old E light bulbs I think of the time I ran into a ghost one night when I was doing our annual 90 minute E light test! 

Hospitals must harbor plenty of ghosts--patients, doctors, nurses, administrators, and facility maintenance folk!

[Ed Kennell 39,935]

1 hour ago, Racinbob said:

 

100% correct. Can I blame it on not having finished my first cup of coffee? 

            Works for me Bob.

 The light output actually is cut to about 25% their norm

 

I salvaged the 6v Emergency lights in my building when they were all replaced due to leaking batteries.

The bulbs actually fit in the Wheel Horse housings.  The bulbs must have lasted forever as I never got a complaint from a buyer of a tractor I flipped that the lights were dim when he replaced a bulb.

[squonk 42,030]

1 hour ago, Handy Don said:

Hospitals must harbor plenty of ghosts--patients, doctors, nurses, administrators, and facility maintenance folk!

1 out of 10 of us employees has a ghost story or 2. Doesn't help that one of the attached buildings ( where I ran into said ghost) was an old funeral home!  1 ghost got into the building automation in the new building in 2015. Took 2 years to eradicate it. 

Edited February 26 by squonk

[Pullstart 63,750]

On 2/25/2025 at 6:06 PM, Handy Don said:

(Unless BOTH lamps blew at the same time! )

 

That happens all the time in the service industry.  “I replaced your gas valve, blower and pilot and you’re all set!  Simple as a full rebuild!” 
 

I used to teach that out of people all the time.  How can two components fail at the same time, when only one is doing work at a time?

[Handy Don 13,139]

20 hours ago, squonk said:

1 ghost got into the building automation in the new building in 2015. Took 2 years to eradicate it. 

Gremlin? 😈

[Handy Don 13,139]

53 minutes ago, Pullstart said:

How can two components fail at the same time,

The classic service tech conundrum--balancing the two directions.

Either put it back together after the first-found problem is fixed and then discover that there is still a problem elsewhere or, sometimes with little evidence, replace/repair stuff not yet proven to be faulty. Experience, instinct and a good feel for the customer’s attitude/appetite/expectations are the only guides!

[adsm08 2,463]

10 hours ago, Pullstart said:

That happens all the time in the service industry.  “I replaced your gas valve, blower and pilot and you’re all set!  Simple as a full rebuild!” 
 

I used to teach that out of people all the time.  How can two components fail at the same time, when only one is doing work at a time?

 

On the other hand, I frequently recommend replacing light bulbs in pairs.

 

My thought process is that for things like brake lights, head lights, and makers, unless one burns out how often is one on without the other? So if they are always on together, and one burnt out, what does that mean for how long the other will last.

 

 

There is also the question of the trouble involved in getting at things. My wife's car needs a torque converter, the clutch in it is worn out and starting to slip, but that's really the only thing wrong right now. But the thing has 165K miles on it. I'm not going to the trouble of taking that transmission out and doing anything less than a full overhaul.