I'm working on my old truck and adding a couple of old switches that have a built-in indicator bulb - that's not replaceable. How do I check with a multimeter to see if it's a 6 volt, 12 volt, or even a 24 volt (aircraft) bulb? Thanks
not sure how to check without taking it apart and looking to see if it has numbers on the bulb or not. But if it is a "non-serviceable" bulb, I'd say its 12 volts. when stuff was 6 volt it was made to be serviced. post a picture of the switches you are using, and we might be able to help better.
A multimeter can't do that. What you can do is to try the light on first 6V, and then go to 12V and 24 if it seems far too dim. If you go above what it's made for it'll probably burn out very fast.
That's a tough one... If the lamps are neon, they won't light at all at voltages below about 60V DC and will read open with a VOM even if the switch is closed. If they are incandescent, without a watt rating it will be impossible to accurately determine. With that said, if you can read across just the lamp (not the switch contacts), as an educated guess I'd expect to see roughly 15 ohms ('cold' i.e. off) for a six volt lamp, double that for 12 and double it again for 24.
Well, you posted more while I was typing. First, that type switch usually has a replaceable lamp by unscrewing the knob. If so, installing the right voltage lamp will do 'ya...
Like other said it should be replaceable, most of the old clamp on lights are. I have a heater knob (and fog lite) that are similar, I used a 14v bulb in it so it would be dimmer. Post up a side shot.
so we can all see it. Of course, a side view would help us see how it's put together. When it's glowing, what is powering it?
Looks very similar to this one posted on the FTE. Maybe the OP on that tread would be able to shed some light on this? (pun intended) https://www.ford-trucks.com/forums/1753144-unity-light-switch-wiring.html
My understanding of electricity is basic, In terms of how it is made, what happens inside the wires, and motors. The flow of electrons. Buut I am the 2 yr old who stuck a bobby pin in the wall outlet. Be sure of what you have before you try to employ it. When I was say 12, I was curious about trying the old type Christmas tree bulb in a lamp socket. The repair electrication could not believe that one whole half of our fuse box was toast. At age 45 I gifted a Buddy a pair of headlights from an old Autocar truck. I assumed he knew that they were 6 volt. He, later on decided that his brother in law's yard tractor would look great with them installed. That tractor was a new age 'Lectronical' machine that never ran again, after the first test start up Be safe. not sorry
The knob on that switch will pull off to expose the small bulb inside it. I have a bunch and they are all like that.
I've got my 6V battery on it. I tried to remove the knob, but I don't want to damage this old switch. I plan to convert my truck to 12 volts anyway, so I will play it safe and assume it's 6v and get on of these for it.. https://vintageautogarage.com/12-volt-to-6-volt-oil-gas-temp-gauge-reducer/ Also, If I install that reducer, can I use a 6 volt relay to power the 12 volt back up light? https://www.speedwaymotors.com/6-Vo...FdREWXtT-nmuHawb1wvd07Jhua_51SpL-b8n6svDV4j9o
DC-DC step-down (buck) converters are around $1 each in 8 packs on Amazon. The L7806 regulator probably inside that 12 to 6v module you linked sells for $7/10 pieces. Dropping 12v to 6v is easy.
Relay you posted rating is 30/40 amps. 12 volts has alway’s required less amperage than 6 volts. So yes you can use a 6 volt relay. Just wire it correctly. 6 volts to coil, 12 volts to switch.
if you drop the voltage to make the light run at 6 volt, you will also drop the voltage to 6 volts out of the switch going to lights or a blower motor or whatever you are trying to switch on and off. spray some wd 40 around the base of the knob, it will pull off and then you can put a 12 volt bulb in it, and you wont need any of these other do-hickys mucking up the wireing.
That reducer may not work. It's designed for a gauge load, usually a milliamp load. You need to know the relay coil current draw, making sure that doesn't exceed the reducer rating. The reducer rating should be at least 150% of the coil draw to allow for current inrush.
Yeah since I'm going to step down from 12v to 6v at the switch, the reverse light will only get 6v as well. I guess I could just run a 6 volt bulb instead of messing with a 6v relay.
That would mean that the step down device has to be able to handle the power consumption of the reverse light too. Depending on what you use that may be a tall order.
The Jalopy Journal
