Abstract: An F.M. demodulation circuit can be rendered insensitive to amplitude, level and waveform variations of the frequency-modulated carrier signal by using a frequency-demodulator (33,37) tuned to half the frequency of the carrier and preceded by a divide-by-two divider (21).

Abstract: A synchronizing circuit arrangement for deriving and processing a synchronizing signal contained in an incoming video signal. The composite synchronizing signal is obtained by means of a comparator stage to which the video signal and a clipping level are applied, and is applied to a line synchronizing circuit. This line synchronizing circuit comprises a synchronization detector for detecting the synchronized state between the line synchronizing pulses obtained and the locally generated pulses of the line frequency. In the synchronized state the peak level detector, by means of which the clipping level is derived, is switched to operate as a mean-value detector which is operative during the occurrence of keying pulses of line frequency occurring during those periods when the video signal assumes a value corresponding with the peak level of the synchronizing pulses.

Abstract: An arrangement suitable for producing pulse-shaped signals whose amplitude is determined by a control voltage in an electronic musical instrument. The arrangement comprises a first transistor having a control electrode to which the control voltage is applied and a main electrode connected to a point of fixed potential via an impedance. The arrangement further comprises means for transferring the output current of the first transistor, which current is determined by the control voltage, to an output in a pulse-shaped fashion. In order to convert the unipolar current pulses into bipolar current pulses the arrangement includes a second transistor whose input circuit is connected in parallel with the input circuit of the first transistor. The output current of this second transistor is subtracted from the output current of the first transistor by means of a current amplifier, the result being available at the output.