| 摘要 |
<p>Supply voltage is applied to the a.f. telephone amplifier (RV) by a battery (BT1) supplied switching amplifier (SV) consisting of a voltage amplifier (T1), a rectifier stage (T2-T4) and a switching transistor (T5) whose switching path is inserted in the telephone amplifier supply circuit. The a.f. voltage to be amplified is applied to the switching amplifier as control voltage. A d.c. voltage indicating the level of the incoming a.f. signal voltage may be taken from the output (Tr1) of the rectifier (T2, T3, T4) and applied to a display.</p> |
