In this day of energy conversion
and high petroleum costs the optimum
consumption of fuel is the goal of all
owners of gas and diesel vehicles. The
tachometer used with internal combustion
engines permits engine revolution
monitoring and with proper driver control
increased kilometers per litre.
The use of electronic automobile tachometers
has not been popular because
their linearity throughout the necessary
RPM range leaves much to be desired due
to their temperature instability. This
report gives details of the design of a
temperature-stable diode-pump automobile
tachometer. The use of an unbalanced
bridge circuit to interface the diode
pump was found to reduce the changes in
pump count caused by a temperature gradient.
The original work, as reported here, was designed for a hand held instrument
to be used by a mechanic.
The identical circuitry has been applied to a digital-readout dashboard-mounted automobile tachometer. Diesel engines have used an inductance pick-up from the timing mark groove on the flywheel