This was a small circuit made for driving an Impact counter. The heart being ICL8038. It must have been a Motor driving a Conveyor, the motor has a feedback attachment called Tachogenerator. Only part of the circuit is shown here. See the image of product here Tacho Counter. The configuration is derived from the Application Notes of Intersil. T
he Voltage from Tachogenerator is Measured on a DPM-DVM and also fed to this circuit after attenuation and filtering. The square pulses of 8038 is used to derive a Logic pulse train for a CD4040. The CD4040 works of 0 and 12V. The above circuit is on +12 and -12. That is the reason R10-R15-Q1 are used. The pulses are 0-12V pulses. The Zero is Virtual like the Virtual Ground in low current power supplies.