The recommended piezoelectric transducer has its maximum output power in frequencies between 700 and 3,000 Hz, but it will also operate in higher frequencies, emitting less power.
The recommended power supply is formed by four AA cells or a 9 V battery.
The very low current drain extends the power supply life.
Our project runs at approximately 18,000 to 40,000 Hz, but you can easily alter this range changing C1 or R1.
C1 can be altered in the range between 470 pF and 0.001 11F, and R1 can be altered up to 100,000 Ω.
The 4093 IC will oscillate in frequencies up to 500 kHz.
A complete circuit diagram of the ultrasonic transmitter is shown in Fig. 1.
The circuit can be housed in a small plastic box. The transducer Will be fixed in the front panel.
IC1- 4093 CMOS integrated circuit
X1 - Piezoelectric transducer or crystal earphone
R1 - 22,000 Ω - pot/trimmer
R2 - 22,000 Ω, 1/4 W,5% resistor
C1 - 1,200 pF metal film or ceramic capacitor
C2 - 100 1 µF, 12 WVDC electrolytic capacitor
S1 - SPST switch
B1 - 6 V (four AA cells) or 9 V (battery)
