Naturally first thing to mind is volts, but it's in a 12 volts system. Now I know they make voltage reducers but would big name aftermarket parts manufacturers and GM implement a voltage reducer to just use a certain bulb ? The bulb is out of an Autometer tachometer but cross references to dash lights also. Local parts stores had same size bulb but it said 14V on the package, both stores said they didn't carry the bulb once cross referenced. I ended up ordering the bulb online but it got me to wondering about the 6.3V or is it an upside down A ?
If you look at things like automotive circuit breaker, they are rated at 14 v, even for the 12v system. I’d suspect the same thing with that bulb. You may have had better luck just looking for a 6 volt bulb, not 6.3.
6.3 volts is a common voltage used in tube equipment, that's what the filaments on many vacuum tubes run at, so it was common to make indicator light bulbs that used the same voltage. If you use a 6.3v bulb in a 12v system, it will burn out. If the bulb is connected to a voltage reducing circuit, it will be OK.
Hopefully the bulb is correct, Autometer doesn't give a whole lot of specs and a price of $12 bucks, a big difference to the $0.27 cents that I ordered
Ya. 6.3 Volts....drop through tach circuit? Autometer No. 86 bulb with or without socket is available through Summit Racing. https://www.summitracing.com/parts/atm-3219?rrec=true
Does that bulb socket have it's own 12v pig tail wire? Looks like circuit board mount powered from the tach. The 14v might work but not be as bright due to different resistance value?
Yes it has it's own pigtail going somewhere into here, I was expecting to find a regular Autometer bulb and socket on the other end of the pigtail, but the bulb loads from the face of the tachometer.
That bulb looks like a #194 which is a super common bulb in trucking for marker lights and clearance lights. A 194 is likely brighter than what you ordered and would therefore make more heat. Probably not what you’re after.
Since the bulb is apparently driven by the tach circuitry, and needs to be 6.3v instead of 12v, the 194 bulb is probably not what is needed here.
"Voltage: 6.3V for long life in 6V applications" this is from the spec you gave in your post . Many cars use 6V electric gauges. Why, because a 12V car may vary from as low as 10 volts to 14 or 15 volts in practice. By reducing the gauge voltage to 6 they stabilize the gauges and prevent wonky readings. While they are at it, they connect the dash lights to the 6V circuit.
The light is actually pretty bright, I don't think it needs to be any brighter or it would be blinding
I get what @Truckdoctor Andy was saying about the 194 bulb. IF you want to go aftermarket, pull the bulb out of the holder (if it comes out) and look at the base, the base might be like a 194 (wedge). "T1-3/4 WEDGE" is the bulb shape and base. The bulb is a GE 86 and might be an a/c bulb. https://www.grainger.com/product/LUMAPRO-Incandescent-Bulb-Incandescent-2FMK3 From Autometer: https://www.autometer.com/replacement-bulb-no-86.html
The little buggers came in yesterday Tested it out today and the $0.27 cent lights work great, don't need no $12 dollar Autometer bulb.
With everything being plastic for yrs now, they're probably afraid if they ran a true 12v light bulb the heat it put out would probably melt the thing... ...
It is intended for a 6 volt system and draws .2 amps in such a circuit. The tach probably may step the voltage down from 12V to 6V internally.
I’ve been running a #86 bulb in my tach for about 30 years now. Works perfect and not too bright or too hot.
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