Programmierbare Schaltuhr (Flipflop Reset-Signal durch Teiler aus Netzfrequenz ableiten)

This filter will pass signals at its centre fre- quency while attenuating signals at all other frequencies. The input signal is fed via Rl to the bases of the complementary emitter folJower T J /T2. Feedback is taken from the emitters of Tl and T2, through the twin-T network to the inputs of the complementary amplifier T3/T4.