This project produces a handy tool for audio (and RF) troubleshooting.

The described audio generator produces squarewave signals between 100 and 1,000 Hz but can easily modified to operate in a wide range with some changes in the original circuit.

The output signal voltage can be adjusted from 0 V up to the power supply voltage, in a range up to 9 V. A complete diagram of the audio generator is shown in Fig. 1.

 

Figure 1 – Schematic diagram of the Audio Generator
Figure 1 – Schematic diagram of the Audio Generator

 

C1 and R1 determine the frequency range of the audio generator.

C1 can be altered to other frequency ranges, but the best way to get a large-band audio generator is to connect a band switch with two or more capacitors as shown in Fig. 2.

 

Figure 2 – Using a band switch
Figure 2 – Using a band switch

 

Using capacitors with values suggested in this circuit, you can generate square signals up to 100 kHz.

All the components can be housed in a small plastic box as shown in Fig. 3.

 

Figure 3 – Housing the project
Figure 3 – Housing the project

 

Frequency is adjusted by R1, and the amplitude is adjusted by R3.

 

Audio Generator

IC1 - 4093 CMOS integrated circuit

R1 - 100,000 Ω - linear potentiometer

R2 - 10,000 Ω, 1/4 W, 5% resistor

R3 - 1,000 Ω - linear potentiometer

C1 - 0.022 µF - ceramic or metal film capacitor

C2 - 100 µF, 12 WVDC electrolytic capacitor

C3 - 0.01 pF ceramic or metal film capacitor

S1 - SPST switch

B1 - 6 V (four AA cells) or 9 V (battery)

 

 

Datasheets


N° of component