Headlights ...dropping voltage on Low side

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Model T Ford Forum: Forum 2014: Headlights ...dropping voltage on Low side
Top of pagePrevious messageNext messageBottom of page Link to this message  By Brian Mettling on Wednesday, June 25, 2014 - 07:54 pm:

hi all...

I just put new headlight reflectors in my 22 touring, and also put on the early clear lenses. They look great. I wanted to drop the voltage at the Low side to drive the car with an "edison" bulb look and have a softer glow. I was considering putting in a rheostat or resistor to drop the voltage on the low side to achieve this. Maybe try 6v to 3v. Anyone ever try this.... or am I nuts?

attached is a pic of an edison bulb. I have them in the vintage fixtures around the house, but every switch needs a rheostat to drop the voltage.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange on Wednesday, June 25, 2014 - 08:07 pm:

Perhaps you could rearrange the wiring so that the bulbs are in series when in the low position and in parallel when in the high position? :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Wrenn on Wednesday, June 25, 2014 - 08:08 pm:

Thats a cool bulb! Always wanted at least one, but would love to have 'em all over the place. Is yours a vintage original, or a re-pop, if there are any such things.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Brian Mettling on Wednesday, June 25, 2014 - 09:10 pm:

Tim- here's the bulbs. They are expensive, about $9 a piece. But if you put them in a regular outlet they will shine bright and you can't see the filament. Like I mentioned, gotta have and adjustable wall switch to get that soft glow

http://www.homedepot.com/p/Globe-Electric-60-Watt-Incandescent-S60-Vintage-Squirrel-Cage-Medium-Base-Light-Bulb-01321/205143832


Top of pagePrevious messageNext messageBottom of page Link to this message  By JohnH on Wednesday, June 25, 2014 - 09:11 pm:

Brian,
It's perfectly feasible, and the easiest way is to switch in a resistor when required. The resistor needs to be a high power type and the resistance only a couple of ohms or less. An ignition coil ballast resistor would do the job. You might need two such resistors in parallel if the lights are too dim. I use a similar setup to use my rear light as a parking light and brake light.
Tim,
Those antique bulbs are available new. Some lighting stores sell them, otherwise do as I did and buy them on ebay. However, be warned that they are not very bright - the filament runs at a lower temperature than a normal bulb. As a rough guide, I found a 60W antique repro lit the room to the same brightness as a normal 25W bulb, and with a much more orange light. They're sold more for decoration than as something to light every room with.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Brian Mettling on Wednesday, June 25, 2014 - 09:34 pm:

John, thanks. Would this one do the job?

http://www.ebay.com/itm/1-6-OHM-IGNITION-COIL-BALLAST-RESISTOR-/161329776549?pt= Motors_Car_Truck_Parts_Accessories&hash=item25900107a5&vxp=mtr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Thursday, June 26, 2014 - 07:25 am:

Could you use a 12v bulb on 6v and get the desired effect?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Wrenn on Thursday, June 26, 2014 - 09:03 am:

Thanks Brian! For as many times as I've been to H.Depot, I've never noticed them. Maybe have to order online...I'll go to your link now and check it all out. Gonna buy some!
Thanks again
Tim


Top of pagePrevious messageNext messageBottom of page Link to this message  By George_Cherry Hill NJ on Thursday, June 26, 2014 - 09:23 am:

Hal, that is the answer as far a lamps go...but I don't think Brian wants a single standard filament, he's looking for the spiral of early Edison lamps or a Marconi Bridge filament arrangement? I 'think' and only thing that Edison did have some curly-que filament lamps in his first miniatures but not sure they survived into the tungsten era...and even if memory serves me correct, that miniature had a screw base. But if so, and one could be found I'll bet that they will be going for over 100 bucks a lamp :-( So that's probably off the table.

Brian, generally, a lamp will just begin to change from glow filament to basic illumination at about 1/2 of the rated voltage. I've seen some that will trigger at this point, some that won't...so call it rule of thumb.

Your best bet to do what you want is to find some 2.0" globe lamps with the TeePee filament, in 12 V and do as Hal suggests. Lamp #1020 in modern lamp lingo is a possibility. Try it first if possible as if it won't trigger at 50% voltage, then all you'll have a bright red filament and no real glow.

There are lamp rerating tables all over the place yet none of them really agree. Various experts use the way they were taught and get by. Others insist on only designing to use lamps at published voltages so there are no questions.

My Dad started instrumenting airplane cockpits in the late 20's and then was Brewster Chief Instrument Engineer from sometime in the 30's, and then was placed into the Navy Aeronautical Instruments Laboratory from WW2 on. Using his rules of thumb which he taught me...the 12 lamp on a 6 supply....current draw will be ~25% less than lamp nameplate rating...CP will only be 9% of the 12V rating (but should still trigger illumination) and the good part is that if it triggers to illumination, the lamp will last 4000 times the nameplate rating at 12V.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Brian Mettling on Thursday, June 26, 2014 - 11:32 am:

wow, thanks George. I'll out the suggestion and go shopping today. I'll post what I figure out


Top of pagePrevious messageNext messageBottom of page Link to this message  By Willie K Cordes on Thursday, June 26, 2014 - 11:43 am:

Mark, I think the bulbs with the high and low use a common ground (the socket). Series wiring would be almost impossible with that bulb.


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