This is the circuit I used for a tacho on a diesel engine in a boat. The hall device was triggered by a magnet stuck on the crank pulley. You don't need fancy circuits on the 12v supply line, as ive used this basic circuit in vehicles aswell. The last picture is using a coil to trigger the hall for calibration purposes & 50Hz, which gives 3000rpm in this application.View attachment 74065 View attachment 74066 View attachment 74067

i need your help in one same project

MOD NOTE: Necrohijack split from this thread.

You now have your own thread to focus on your specific problem.

 

!0 yr old thread!
There is no question in your post either !!!??

 

To count ignition pulses to read RPM an LM2917 is not the best choice because it is a ANALOG TACHOMETER device. It will drive a meter very well as a great analog tachometer.
forty years ago I designed a digital input circuit for a counter as part of some development tools package. That input from a clamp on pickup used a series 1K resistor followed by a standard 2-diode clamper pair to feed a 7414 hex schmit trigger to square the signal. The challenge was setting the time base frequency so that the measuring time would provide a direct RPM count.

 

Thank you so much eetechoo.

Can you please explain the LM317L circuit. what is its function????? Why is it there??

I was wondering also because the LM2917 includes an internal zener diode regulator. So it must have some resistance in the voltage supply line. The LM317Lis a voltage regulator which will be needed for the digital counter portion of the system.

 

Simple & efective set up I used on a Yanmar diesel on my boat. Salvaged VDO tacho which didnot suit so only using its meter. Hall sensor sensing small magnet on crank pulley. Worked great.