| 摘要 |
<p>A toy car travelling along a track, has a warning lamp mounted on the roof. This lamp is mounted on a circuit board so as to project through the roof. It is operated by a circuit so as to give a flashing light. The circuit includes an astable multivibrator with two transistors (Tr1, Tr2) which gives it the frequency of the flash. This is determined by a resistance capacity network (C1, C2, R2, R4). The collector of Tr2 is connected by a resistance (R6) to the amplifier transistor (Tr3). This operates the light diode (LD1). A resistor (R5) and a capacitor (C3) stabilise the voltage.</p> |
