Figure 1 – Adding sound
One or two diodes placed in parallel with the loudspeaker avoid the voltage drop in this component (because of its impedance), keeping the torque and speed constant.
Any small loudspeaker (2 to 4 inches and 4 to 8 ohm) can be used here. This block uses two diodes and is indicated for the current flowing only in one direction.
The diode is necessary, as the buzzer is powered from the reversed voltage generated in the switching process by the inductance produced by the motor,s coils.
Using Piezoelectric Transducers
Small piezoelectric transducers placed in parallel with dc motors will reproduce the signal generated in the switching process as shown by Figure 2.
Figure 2 – Using a piezoelectric transducer
