| 摘要 |
<p>A vital electronic circuit arrangement which includes a low-pass filter network for passing a.c. signals. A transistor amplifier for amplifying the a.c. signals and for supplying the amplified a.c. signals to a step-up transformer. The transformer includes a controllable tap primary winding for discretely varying the turns-ratio of the transformer in accordance with the frequency of the a.c. signals.</p> |
