That’s some damned ingenious engineering right there.
@mx5info3 ай бұрын
I agree. It delivered a reliable solution. Mazda was not the only one using this approach. I have seen it in Honda forums as well. With the contacts in that glass housing and the use of a gas in the housing, the contact cannot corrode either.
@RobWhittlestone3 ай бұрын
Very clearly and well explained. It makes me wonder what the maximum frequency such a reed switch can accurately follow to provide a reliable square wave output. Is there any data on that? I found some data on miniature glass reed switches with resonant frequencies upwards of 3kHz so if the magnetic field is significantly below that, i suppose they should operate reliably. Contact bounce and bounce time might degrade the square wave when the switching frequency gets too high, I imagine.
@mx5info3 ай бұрын
On one of the pictures I have found, there is some text on the back of the gauge face indicating that 60 mph = 1024 rpm for the speedometer cable. When we assume a pretty optimistic top speed of 135 mph (217 km/h) we arrive at 2304 rpm. That means 37.5 rotations per second. With each rotation providing 8 flanks, 4 up and 4 down, the maximum frequency for the signal would show 300 flanks per second. I guess the frequency for the signal would then be 150Hz. That would mean the Reed switch is not stressed at all. 😎
@RobWhittlestone2 ай бұрын
@@mx5info Sounds good and a new way for me to provide a variable timing signal! All the best, Rob in Switzerland