electronic dog

electronic dog To produce a faithful reproduction of the voice of man"s best friend, we have borrowed several ideas from our music synthesizer. When push button switch S2 is pressed, the frequency of voltage-controlled oscillator (VCO) Al-A2changes in about an eigth of a second from almost 0 Hz to a preset- table value of 100...1000 Hz. That signal is passed through band-pass filter A 5-A6, the centre frequency of which corresponds with the highest VCO frequency. Voltage-controlled amplifier (VCA) Ti ensures that the single pulse generated by the VCO when S2 is open cannot be heard. Gates N1and N2 form a monostable relaxation oscillator. When S2 is closed, a short pulse appears at the output of N2 that charges capacitor C2. Because of R3, the pulse shape will be as shown in figure 1. This pulse controls the output frequency of the VCO as also shown in figure 1. Poten- tiometer P1determines the highest frequency: its setting depends on whether you want the sound of a yap- ping pood...