The telephone amplifier circuit, as its name suggests, amplifies the incoming calls to be heard in a room. while in conversation with a distant subscriber the voice is so faint that is barely heard, hence, this amplifier circuit does the correction.
Hardware Required
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Telephone | – | 1 |
| 2. | IC | LM386 | 1 |
| 3. | Radio Output Transformer | – | 1 |
| 4. | Diode | 1N4007 ,1N4148 | 4, 2 |
| 5. | Zener Diode | 12V | 1 |
| 6. | Capacitors | 0.1µF | 3 |
| 7. | Electrolytic capacitor | 1000µF/25V 220µF/16V | 1 1 |
| 8. | Variable Resistor | 10KΩ | 1 |
| 9. | Resistor | 10KΩ | 2 |
| 10. | Speaker | 8Ω | 1 |
Circuit Diagram
Circuit Explanation
The circuit uses an inexpensive amplifier LM386 to perform the task. Furthermore, circuit does not need an external power source as it draws power from the line. Next, the full bridge rectifier of 1N4007 rectifies the power drawn from the line. Also, bridge confirms that the voltage is positive with respect to the circuit’s ground. Radio output transformer, then, steps down the signal. Moreover, the voltage is dropped to 12V by Zener diode to power the IC LM386. Once the IC is powered, the LM386 does the amplification of the signals received. In addition, a 10KΩ variable resistor adjusts to the desired level of volume.
Application
- Amplifier for landline corded telephones.
- Portable landline amplifiers
