Abstract: A preamplifier circuit for amplifying a video signal reproduced by a magnetic head includes a positive feedback circuit for reducing an input capacitance thereof. A negative feedback circuit may be added thereto for stabilizing an operation of the preamplifier.

Abstract: A rotary-head type magnetic tape recorder for recording a video signal and an audio signal on a magnetic tape by means of a rotary head controlled on the basis of the video signal. Difference is determined between a rate at which the digital audio signal is recorded on the recording medium and which is determined by the video signal and a rate of input data determined by a sampling frequency of the audio signal for a number N of samples of the digital signal to be included within one field period synchronized with the video signal. The number of samples for one field of input data is set by preparing on the basis of the result of detection of the difference in rate a first field containing a number of samples greater than the number N within and a second field containing a number of samples smaller than the number N.

Abstract: A framing code detector includes a shift register supplied with a received framing code and a number of EX-OR gates each having one input connected to a respective stage of the shift register and another input which is supplied with a respective bit of a stored pattern having the inverted form of the anticipated framing code to be received/ a counter is provided for counting the number of times all outputs of EX-OR gates become "1" during a predetermined period, and an identification signal is produced when the count value of the counter is greater than a predetermined value.