| 摘要 |
PURPOSE:To facilitate an easy adjustment of the trigger level with a simple constitution of the circuit, by generating the trigger signal which turns to a high level only in case it receives the reverse DC voltage of the antenna's input level and a low-level signal at the intermediate frequency band. CONSTITUTION:Resistance R1 decides the working start value of transistor (TR) Q1 by the antenna's input level. And TRQ1, Q2 are turned on and off respectively when DC voltage E1 of about 0.6V or more is applied to terminal I1 in order to secure a high level for the collectors of these transistors. On the other hand, applied voltage E2 of terminal I2 turns to a low level during the reception in a narrow frequency range centering on the intermediate frequency. Accordingly, if this low voltage is applied to terminal I2, the collector of TRQ3 turns to a high level along with trigger signal E0 kept at a high level. And TRQ2, Q3 have their collectors connected directly to each other. Thus signal E0 turns to a high level naturally if the base input has a high level. In such way, the adjustment of the trigger level can be facilitated with a simple constitution of the circuit. |
