Try AO services
Their device has a light & a buzzer to my knowledge
Back in the 60’s & 70’s this was a Honda dealer special tool / long discontinued
Br
Job

email (option): Jonnyob1atgooglemail.com

Thanks for these responses. I can see the point of an audible indicator.
I looked up AO Services & their device seems to be the same one the Magneto Guys sell, the AO instruction sheet has the Magneto Guys logo on the bottom. And there's no mention of a beeper.

Here is the one I use.

https://www.lasaero.com/products/article/P029YHTZP

I have a mate who is a light aircraft mechanic so borrow his when I need too.. Handy tool, but if you use the old fag paper method, bin the fag paper and use a slice of crisp packet, you can put tension on these without it tearing.....

If you look in Irving’s Tuning for Speed there’s an illustration of a torch bulb and battery being used to set mag timing. All very mid 20th century!

I use a Magneto Guys timing light, very useful and accurate. Worth every penny, although the insulation on the alligator clips makes them a bit fiddly to get attached properly