Automatic tuning circuit for receiver blocks - is used during manual tuning adjustment using OR-gate controlling switch

摘要

The tuning circuit for a receiver passes the adjustable tuning voltage to a circuit that makes the automatic tuning circuitry ineffective for the duration of any change in the tuning voltage caused by manual adjustment. The adjustable tuning voltage is applied to the non-inverting inputs of a first and second operational amplifier via a delaying integrating circuit, and to the inverting inputs directly without a delay. The second amplifier output is passed to an OR-gate, and the first amplifier output to an inverter. The OR-gate controls the switch coupled to the automatic tuning circuitry.