Single shot multivibrator using seriesresonant cross-coupling for resetting fixed time interval after triggering

953,072. Flip-flop circuits. INTERNATIONAL BUSINESS MACHINES CORPORATION. July 29, 1960 [Aug. 26, 1959], No. 26546/60. Heading H3T. A resonant circuit is included in the coupling between the two stages of a flip-flop circuit to control the duration of the output pulse from the second stage, and means are provided to inhibit oscillation of the circuit during the rise and fall periods so as to reduce the rise and fall times. As shown, one of the couplings between two complementary transistors T1, T2 includes a series resonant circuit 22 so that an input pulse at terminal 1 will render transistor T1 conducting and this in turn will render T2 conducting, the feed-back through 21 maintaining T1 conducting even if the input pulse terminates. In the absence of the third transistor T3 the current through the resonant circuit would oscillate sinusoidally for half a cycle increasing to a maximum and decreasing to zero, so maintaining transistor T2 conducting for that period and at the end of the period both transistors would revert to the non-conducting state. However, in order to steepen the initial part of the current waveform applied to transistor T2 a normally conducting transistor T3 is connected across the capacitor 200 so that current rises in inductance 100 exponentially instead of sinusoidally. When transistor T2 becomes conducting sufficient current flows in the coupling network to bias transistor T3 to cut-off so that after this point the current through circuit 22 increases in resonant fashion. In a similar manner, transistor T3 becomes conducting again while T2 is being cut-off so the trailing edge of the pulse is also steepened.