JPS6181273U - - Google Patents

Description

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of the FM modulation/demodulation circuit of the present invention, and Figs. 2 and 3 show the modulation characteristics and FM characteristics of Fig. 1, respectively.
An explanatory characteristic diagram showing demodulation characteristics, Fig. 4 is a conventional FM
The modulation and demodulation circuit diagrams, FIGS. 5 and 6, are explanatory characteristic diagrams showing the modulation characteristics and FM demodulation characteristics of FIG. 4, respectively. Explanation of main figure numbers, 1... Multivibrator, 2
...first transistor, 3...second transistor, 4...third transistor, 5...fourth transistor, 6...fifth transistor, 7...sixth transistor, 8...seventh transistor, 9... Eighth transistor, 10...Ninth transistor, 11
, 14, 15, 32...recording/reproduction switching switch, 1
2... Constant current gap, 16, 17... Level shifter, 18
...Multiplier, 19...Limiter, 21, 22...Input terminal, 23, 24...Output terminal, 25...Low pass filter, 30...First DC power supply, 31...Second DC power supply.

Claims (1)

[Scope of utility model registration request] In an FM modulation circuit that performs FM modulation of a luminance signal during recording and FM demodulation during playback, a first transistor and a second transistor whose emitters are connected in common, and an emitter at each collector of the first and second transistors are provided. third and fourth transistors connected to each other; fifth and sixth transistors having emitters connected to respective collectors of the third and fourth transistors; and between the emitters of the first and second transistors and ground. between the connected first recording/playback switch, the second record/playback switch connected to the bases of the first and second transistors, and the recording terminal of the first record/playback switch and ground. It consists of a recording signal transistor with a collector-emitter path connected and an oscillation capacitor connected between the emitters of the third and fourth transistors. The outputs of the fifth and sixth transistors are connected to a second DC power supply via a switching means, and are operated by the first DC power supply in response to a recording luminance signal applied to the base of the recording signal transistor during recording. The oscillation output is derived from the side, and the reproduced FM signal and the second
The output signals of the fifth and sixth transistors operating on the DC power supply are input, the output of the multiplier is passed through a low-pass filter to derive the demodulated output, and the voltage of the first DC power supply is inputted to the second DC power supply. This is an FM modulation/demodulation circuit that has a voltage higher than that of the DC power supply and is characterized by improving the quality of playback.