A tone control circuit is an electronic circuit that consists of a network of filters that modify the signal before it is fed to speakers, headphones, or recording devices by way of an amplifier. It allows a listener to adjust the tone of the sound produced by an audio system to their liking, for example, to compensate for inadequate bass response of loudspeakers or earphones, tonal qualities of the room, or hearing impairment. This tone control circuit is based on a low noise JFET input operational amplifier TL072 integrated circuit. This operational amplifier gives low noise output with few external components, it needs +ve and -Ve dual bias supply for better operation.
Hardware Required
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Operational Amplifier IC | TL072 | 1 |
| 2. | Resistor | 1KΩ,100KΩ,2.2MΩ,10KΩ | 2,2,1,2 |
| 3. | Variable Resistor | 100KΩ | 4 |
| 4. | Capacitor | 1uF,100pF,22nF,220nF,2uF,2.2uF | 1,1,1,1,1,1 |
| 5. | Connecting Wires | – | – |
| 6. | Battery | 15V | 1 |
Circuit Diagram
Working Explanation
As we can see in the circuit, the main part of the circuit is the operational amplifier IC TL072. First, an audio input signal is applied to the operational amplifier with a balanced circuit (which is made by resistors and capacitors). Here feedback for amplifier resistors R3 and R2 is placed. Now the output from the amplifier is applied to the tone control circuit, the tone control circuit controls bass, treble, and balance effects in the output audio signal. This output to the speaker is taken from the volume control variable resistor VR2. In the last to give signal extension for other channel amplification, a balance control VR3 variable resistor is used.
Dual power supply for operational amplifier
As we know that for perfect amplification, there is a need for a dual power supply for Op-amp IC TL072. Therefore here we have designed a dual supply circuit with simple few components. This is constructed by using a step-down transformer (12-0-12 V) center tapped output, 1 Amps bridge rectifier for AC to DC conversion, and filtering capacitors. This step-down transformer converts the higher AC voltages into lower, then this step downed AC supply is rectified through a 1 amps bridge rectifier. This rectifier gives +ve and -ve supply. Further, the rectified DC is filtered by capacitors. We can get a +15V-0- -15V dual supply from this circuit.
Applications
Tone controls are found on many sound systems: radios, portable music players, boomboxes, public address systems, and musical instrument amplifiers.
