1398755 Semi-conductor pulse circuits ITT INDUSTRIES Inc 8 Nov 1972 [12 Nov 1971] 51447/72 Heading H3T Frame synchronizing pulses are extracted from a TV signal by integrating them (T1, T2, R1, R2, C1, C2) and line pulses removed by differentiating them. The circuit is said to permit smaller capacitors Cl, C2 to be used than hitherto. The composite line and frame sync. pulse signal (A, Fig. 2, not shown), is applied at A, and its complement at B. C2 is rapidly charged through T1 by the relatively longer pulses of the frame sync. signal, with a time constant R1.C1/B1 where B1 is the current gain of T1. The charge is held by the larger time constant R2.C2.B2, where B2 is the current gain of T2, until the end of the frame sync. pulses. The line sync pulses are differentiated by R1.C1. The output (D) appears at T2 emitter. Biasing is provided by R4, R5, and feedback optionally by R3. A diode connected transistor T3 effects temperature compensation. To suppress the remaining portions of the line sync. pulses in the output D, a threshold circuit may be used, such as a differential amplifier.
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