Vintage vibrating reed tachometer - GIF

[Jon]

Vintage vibrating reed tachometer.

[jimfols]

I read of F1 teams using Acoustic Tachometers to get competitors RPMs at various places on the racetrack.

[hemmjo]

I used to use one exactly like that in the shop, back in the late 60's and early 70's when I was an outboard mechanic in a marina. Used it sometimes on out on boats to help customers select the right prop to allow the engine up into the correct RPM range and not over rev.

Always fascinated me to watch the vibrating needles move up the scale as the engine accelerated.