02-03-2020, 04:26 AM
recap VSS1, 4 pulses per turn of PROP shaft. (the secret told due to above 1 photo)
The tire wheel axle turns 744 turns per mile on stock P205-75-r15) USA spec, car.
the prop shaft turns 5.12 times that, faster. at 3809 turns per mile and tone wheel does 4 times that. 15,237 clicks per mile.
so at 60MPH that this 60x that 914,227 clicks per hour.
to compute that to Hz (pulses per second (leading edge) divide that by 60x60 or 120, (min x seconds) = 7618 Hz, or pulses per second. at 60MPH.
the scaling at 60MPH corrected with the black box would be 110% more is 8380 HZ out.
the problem to make a box is lacking a live signal to test, and debug. a trans on a bench and drill motor turning trail shaft would work but is too OVER THE TOP hard.
what I'd do is get a hobby box with zero crossing detector inside, with power, from say 12vdc to 7805 REG (temporary this there are vastly better regulators for car ) to 5vdc
then connect box to car and VSS1, and make sure the zero detector works , I use the free ZD, in the above posted chip, LM2917 . nice chip that is.
then with that working, make the other side that scale Vout from LM2916 to your VFC chip. scaled at 110% and tuned by you.
or use Arduino way.
a coding 99% exercise. (+ ZCD )
The tire wheel axle turns 744 turns per mile on stock P205-75-r15) USA spec, car.
the prop shaft turns 5.12 times that, faster. at 3809 turns per mile and tone wheel does 4 times that. 15,237 clicks per mile.
so at 60MPH that this 60x that 914,227 clicks per hour.
to compute that to Hz (pulses per second (leading edge) divide that by 60x60 or 120, (min x seconds) = 7618 Hz, or pulses per second. at 60MPH.
the scaling at 60MPH corrected with the black box would be 110% more is 8380 HZ out.
the problem to make a box is lacking a live signal to test, and debug. a trans on a bench and drill motor turning trail shaft would work but is too OVER THE TOP hard.
what I'd do is get a hobby box with zero crossing detector inside, with power, from say 12vdc to 7805 REG (temporary this there are vastly better regulators for car ) to 5vdc
then connect box to car and VSS1, and make sure the zero detector works , I use the free ZD, in the above posted chip, LM2917 . nice chip that is.
then with that working, make the other side that scale Vout from LM2916 to your VFC chip. scaled at 110% and tuned by you.
or use Arduino way.
a coding 99% exercise. (+ ZCD )
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