On Tuesday, January 31, 2017 at 1:08:32 AM UTC-5, Bob Engelhardt wrote:
On 1/30/2017 6:12 PM, wrote:
I don't really know about what you're talking about, but really old tachometers had centrifugal weights and displaced according to the force on the weights.
...

3:16 here https://www.youtube.com/watch?v=VMP7fW7tj3w

BTW, I caught that jerking tach. I just got caught up in the car. g

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Ed Huntress