We found this version of the automotive tachometer in a 1980s publication. Variations from other sources appear elsewhere in this section. The indicator is a 0 to 1 mA milliammeter.
The integrated circuit is not common nowadays since the configuration was obtained in Motorola's Linear...
This amplifier was found in Burr-Brown documentation from the 90's. The gain can be programmed by resistor...
In the figure we have an IF amplifier step using a MOSFET. The circuit was found in a 1980s...