siren

siren Agsrimi In spite of its modest configuration, the circuit shown here is capable of generating quite a sound. This is made possible by the n-channel MOSFET, T1, which drives the loud- speaker. Such a MOSFET can be driven direct by CMOS logic circuits, and the type chosen here has an output (=drain- source) resistance of only three ohms. Moreover, its drain current can be as high as 1.7 A, while the maximum drain-source voltage is 40 V. These parameters are independent of the polarity of the applied voltage, since the device has internal diode pro- tection. Since the MOSFET is virtually indestructible, it is perfectly all right to load it with just a loudspeaker. The circuit can be controlled simply from a computer, and is operated by making the ENABLE input logic high (which can also be done with a simple El ... N3 = 3/41C1 = 4093 switch instead of a computer). When the input at pin 5 of gate N2 is high, the pulses from Schmitt trigger N1 cause N2 to oscillate. The output of ...