| 摘要 |
PURPOSE:To prevent an unfair practice with a simple constitution, by using a ripple voltage as a disturbing signal. CONSTITUTION:A signal including a ripple voltage obtained from an AC rectified at a diode 27 is inputted to a collector of a transistor (TR)36. When a specified charge is paid, a moving piece 34 of a switch 31 is connected to a terminal 35. The TR36 is turned off and no ripple voltage is inputted to a channel selecting circuit 8. If no charge is paid, the moving piece 34 is connected to a terminal 32. The TR36 turns on and the ripple voltage inputted to a terminal 6 is inputted to the channel selecting circuit 8. The ripple voltage appears at the collector of a TR42 and is superimposed on a tuning voltage via a capacitor 49, resulting that normal receiving is not done. |
