Only a qualified electrician or service personnel should perform any electrical troubleshooting or maintenance. At no time should circuit continuity be. Fig. 1: RPM meter circuit Diagram. The circuit has three stages—pulse detection, frequency-to-voltage conversion and display of voltage by the LED bar graph. To Wiring diagram for MAGNETIC sensor / SWITCH CONTACT input signal . Average measurement maximum time (tMAH) and time limit (tLiM) (tachometer mode only) The sensor side of the switch has an X on it and is located on the opposite side of the switch from the wiring cable. Refer to the top view diagram below. TheInstruction Manual. Digital Tachometer/ Elapsed timecounter/ Time width meter/ Flowmeter. Electric Shock. Be sure to turn the power OFF when wiring as well DIGITAL RPM METER SCHEMATIC datasheet, cross reference, circuit and application notes in pdf format. Fig.2: Schematic Diagram of 741c. Here in our circuit we use this device to convert the analog voltage signal into digital voltage signal.