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Tldr: Can I use a 6v timing light on a 12v truck if I power the timing light with a 6v?
I got this old timing light years ago at an estate sale because I thought it looked cool. I tried to use it awhile ago but I’ve never used a timing light and it didn’t seem to work. I recently replaced the distributor in my truck and got it close. I thought it would be good to check with a timing light so I dug out this old thing. Yep, still doesn’t work. What is going on inside?
Oh, I just found this manual to something similar: https://archive.org/details/allen-model-e-323-operating-instructions
It looks like that one in the manual is simpler, or a different bulb. There is a schematic, but it doesn’t match mine.
It looks like this may be non-inductive! I was clamping to the spark plug wire insulator near the distributor. It looks like this kind clamps to the conductor at the spark plug.
I’m not sure how it works but I could guess. The first thing I notice is the 6v vibrator, so this is for a 6v vehicle. The battery cables go to the vibrator. The vibrator and relay turn the 6v dc into a square wave that is fed into the transformer. The transformer steps it up to 500 v A/C. The 500VAC square wave is smoothed to a modified sine wave with the capacitor. That looks like a Selenium rectifier, it would be to turn the 500VAC into 500V dc for the bulb. I’m guessing it’s a Xenon bulb. There is also an incandescent bulb next to the capacitor, could be used as an opto-coupler, or opto-isolator I don’t know. It would be nice to get a schematic of this one.
Can I use this to set the timing on my truck? Maybe? Can I connect a 6v battery to power the timing light, and connect the 6v battery negative to vehicle ground, and then tap into the #1 spark plug for the pulse? I don’t even know if this works as-is, I may have fried it when I connected to 12v.
What would it take to modify this to work with 12v? Replace the 6v vibrator with 12v. The transformer would put out 1000v, so the transformer would need to be replaced with a 12v to 500-500. If the transformer remained as-is, the capacitor would need to be upgraded, and I don’t know if the bulb could take double the voltage. There’s also the issue of the spark voltage. This is designed to use on points systems, my truck has a late 80’s TBI engine with electronic ignition. I thought I read the coil puts out more voltage on modern vehicles. What is the worse that could happen?

The timing light doesn’t care where it gets it’s power from so if it is a 6 volt light just set a 6 volt battery close to to your truck and hook pos to pos and neg to neg then the plug lead to #1.

You didn't show the wiring connectors, but similar lights we used back in the dark ages had to have the trigger lead in series witgh a plug wire so the spark impulse passed throught the trigger on the way to the plug. Use a 6 volt battery to power the light, and have fun tinkering with your antique for a while. Then do yourself a favor and buy an Innova timing light that has a brighter flash, a delay function to allow you to check timing advance, and a tachometer built in. Those lights can even be used on 6V systems by powering up with a small 12V battery.
Jerry

Thanks for the replies! That gives me the nudge to continue.
I read up some on 6v vs. 12v vibrators and found that vibrator servicing was a typical procedure to smooth out pitted contacts in the points type units. Reed contact vibrators were more durable and more expensive. I’ll set up a voltage divider with a couple resistors to get 6v from a 12v battery and try to get the vibrator working on the bench.
The trigger lead is just one conductor with one clamp and one very disintegrated rubber boot. There was a short length of the end of a plug wire in that clamp, maybe an easy way to break out the spark? I’m not sure how I’m going to attach the lead to the modern plug wire, I don’t know if the boots are molded on, or if I can slide one out of the way.