In this Tutorial, we are going to make a “Simple condenser mic preamp circuit using 2N3904”. Preamplifiers (Preamp) are typically the initial stage of any amplifier circuit that picks up the extremely weak signal and amplifies it to pass for additional processing. Also, it raises the circuit’s gain.
The majority of microphone preamps’ main goal is to provide gain to the signal without affecting the sound of the signal. This is challenging to do in practice since most amplifiers introduce some noise and distortion into the signal.
In the making of the circuit, we are using Electret Condenser Microphone. This particular microphone is based on electrostatic capacitors. A condenser microphone is one whose audio pickup component has a condenser-like construction made up of a diaphragm and a backplate directly across from it. A change in capacitance between the diaphragm and the back plate is used to detect the motion of the diaphragm caused by sound.
Hardware Required
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Resistor | 1K, 10K, 27K, 100K | 1, 1, 1, 1 |
| 2. | Capacitor | 10uf | 2 |
| 3. | MIC | – | 1 |
| 4. | NPN Transistor | 2N3904 | 1 |
| 5. | Switch | – | 1 |
| 6. | Battery | 9v | 1 |
Circuit Diagram
Working Explanation
A 9V battery is first connected to this Simple Condenser Mic Preamp Circuit using 2N3904. Then, an electrical current flows via a resistor R1 to bias the microphone. Also, R1 limits the current flowing through MIC1. . The electrical signals change when we deliver a sound at MIC1. The audio signal is then sent through coupling capacitor C1. It will prevent the DC from moving. The signal, however, is quite faint. Therefore, it requires assistance from a transistor Q1 to amplify the signal. The signal then travels to Q1’s base to enable a bigger signal from Collector to reach the output. Finally, the output receives the AC signal from the coupling capacitor C2.
Application Uses
- In recording or raising audio signals/vocals
- In seminars, concerts, live sessions, etc
