cricket simulator

9V 9V 1Nl 51 1T3 2 JJ P1 C1 look 10n 14 T C5 "cl 9V op 1C2 cricket simulator 9+ This simulator gives a faithful repro- duction of the chirping of a cricket. The circuit comprises four oscillators of which the first, Nl, produces the basic high note. The frequency of this note is set by potentiometer Pl such that it lies within the resonant range of the crystal buzzer: the tone is then loudest. To obtain the typical chirping noise, the 4 kHz square wave output of N 1 isamplitude modulated by a fre- quency of 10.. 20 Hz. This fre- quency is produced by oscillator N2 and the modulation takes place in digital frequency changer N4. To make the end-result realistic, the "cricket" must, of course, not chirp continuously but with suitable pauses. This is effected by oscillator N7/N8 and frequency changer N6. The oscillator output has a duty cycle ratio which is directly pro- portional to the ratio of the two sections of potentiometer P4, and can therefore be changed as desired. The durat...