Revealing how old speedos work

[faffi]

https://www.youtube.com/shorts/c2anOscRHDQ

[Dr. Enzo Toma]

Even older, Corbin mechanical speedos ran off a gear drive opposite the sprocket. Common on Harleys and Indians.

[Kiwi_Roy]

The spinning magnet induces a current in the Aluminium disc the current is shorted out so it converts to a torque acting against a hair spring.
Modern electronic speedos are driven by stepper motors with the position calculated by microprocessor.
Speedhut make  whole range of stepper motor instruments.

[PeteS]

Much cooler and older are the Smiths Chronometrics.

https://www.youtube.com/watch?v=VPkX5sy_OiA


Pete

[Kiwi_Roy]

Much cooler and older are the Smiths Chronometrics.

https://www.youtube.com/watch?v=VPkX5sy_OiA


Pete

I agree, the police cars where i grew up used Smiths Chronometric speedos for accuracy
Lots of Brit bikes had them.
Roy

[faffi]

Much cooler and older are the Smiths Chronometrics.

But do they have magnets that stop working if you toss them into water    

[wirespokes]

The mechanical speedometer was created in 1904, if I recall correctly. The really interesting part is that the spinning magnet creates a force field, called eddy currents, that affects aluminum. Who woulda thought?

Why, oh why, did Guzzi ever decide to use electronic tachometers? (a mechanical tach is the exact same mechanism without the added odometer function) I've been trying to figure out how to replace the electronic guts of my multiple dead electronic tachs with a stepper motor, or at least something reliable. I've heard that all modern gauges use stepper motors these days.

[PeteS]

The mechanical speedometer was created in 1904, if I recall correctly. The really interesting part is that the spinning magnet creates a force field, called eddy currents, that affects aluminum. Who woulda thought?

Why, oh why, did Guzzi ever decide to use electronic tachometers? (a mechanical tach is the exact same mechanism without the added odometer function) I've been trying to figure out how to replace the electronic guts of my multiple dead electronic tachs with a stepper motor, or at least something reliable. I've heard that all modern gauges use stepper motors these days.

The V85 is all electronic. No motors or magnets, just numbers on a screen.

Pete

[wirespokes]

All digital. Not as much fun as a needle sweeping the dial.

[Kiwi_Roy]

The mechanical speedometer was created in 1904, if I recall correctly. The really interesting part is that the spinning magnet creates a force field, called eddy currents, that affects aluminum. Who woulda thought?

Why, oh why, did Guzzi ever decide to use electronic tachometers? (a mechanical tach is the exact same mechanism without the added odometer function) I've been trying to figure out how to replace the electronic guts of my multiple dead electronic tachs with a stepper motor, or at least something reliable. I've heard that all modern gauges use stepper motors these days.

That would be Speedhut.
They have a great range of Stepper Motor gauges, they even let you pick out the look colours etc and will even include the Guzzi graphic
I put a pair on a VII Sport I had, great gauges, great people to deal with.
www.Speedhut.com

[wirespokes]

Thanks, Roy. I'm thinking that's the way to go. I'd been wondering if Speed Hut used stepper motors - seems like the best way to go with analog gauges.

Before the pan demic  there was a guy in Italy selling digital tachometers for $80 that could be configured as to length of sweep, pulses/revolution and max RPM.
 
It got mounted behind the original face using the original needle.

Unfortunately, he disappeared (- got him?) otherwise I'd have bought several.