| 摘要 |
A control circuit for a piezoelectric buzzer, notably for automobiles, comprises a circuit for generating alternately two different frequencies and features two input supply terminals (1, 2) and two output terminals (4, 5) for buzzer activation. The control circuit includes a first flip-flop with a first and a second output, of which one carries positive and the other negative voltage. Also provided is a second flip-flop with a first input and an output, the first input connecting to the first and second outputs of the first flip-flop, each via a resistor (R4, R3). The second flip-flop consists of a parallel wiring of a first series connection of a capacitor (C2) and an inverter with Schmitt trigger input (IC1C), and a second series connection of a resistor (R5) and an inverter with Schmitt trigger input (IC1D), while a resistor is wired in parallel with the second series connection. Once a positive supply voltage is applied and grounding established, the buzzer sounds, generating alternately different frequencies f1 and f2.
|
