If the microphone has very weak sound and there is distortion, then this problem can be eliminated with the help of a preamplifier. This is such a device that can amplify a weak signal to the desired volume level. And the sound wave immediately gets amplified into the computer and without extraneous sounds. The amplifier does not have to be bought in a store, but can be made with your own hands.
How to make a DIY amplifier for a microphone
To make a microphone preamplifier that will take energy not from batteries or not pull long wires from another power source, but to recharge it, directly, from a sound card, you need to make a circuit with a phantom power source. That is, such a scheme where the transmission of an information signal and the power of the device occur jointly through a common wire.
This option is the most optimal, because an ordinary battery often runs out, using a battery also requires recharging it from time to time. Using the power supply is also not very convenient, because there are wires that can interfere with movement and third-party interference if necessary. These factors lead to inconvenience of using the device.
Important! The operation of the microphone is based on the property of some materials having an increased dielectric constant to change their charge by the action of a sound wave. And to amplify the microphone signal, you need to set the resistance in the range from 200 to 600 Ohms, and the capacitance of the capacitor should be up to 10 microfarads.
For this purpose, you must have:
- resistors;
- capacitors;
- transistor;
- plug and jacks for connecting the device;
- wires
- housing;
- microphone;
- additional tools - nippers, soldering iron, scissors, tweezers, glue gun.
Amplifier circuit
There are so many ways to assemble an amplifier, but this circuit is notable for its simplicity and it is based on a classic transistor cascade where a common emitter is installed. Also, its assembly does not require the purchase of expensive parts. It will take only one hour of free time to make it. The circuit in operation consumes 9 mA of current, and at rest - 3 mA.
It has two capacitors and two resistors, one plug, a transistor and an electret microphone. The amplifier board turns out to be very small, which can be attached to the plug, if it is slightly larger, then you need to take some plastic part to make the case.
The principle of its operation is such that elements are fed through resistors R1 and R2, in order to prevent feedback in the frequencies of the supplied signal, capacitor C1 is used, but the resistor is needed to eliminate extraneous clicks when connecting to the microphone. The signal comes from the resistor and goes to amplify it on the transistor. Thanks to this scheme, the dynamic microphone signal can be doubled.
Microphone Amplifier: Step by Step
We take a resistor, it will perform the function of a voltage bias. We take the transistor of the KT 315 model, we can replace the KT 3102 or BC847. To make the circuit, we can take a home-made breadboard. We thoroughly rinse it with any solvent before use. To it you need to solder the connectors through which the power is being supplied, also in this way we connect the microphone input and output connectors. We take the connectors and solder to our board. They can be taken from the old DVD player, tape recorder. The switch can be taken from an old toy car. Solder all the details to the board.
To make the case for the microphone amplifier, we take a box of plastic. In it we make holes for the connectors and for the switch. Glue the board to the box and cover with the top of the plastic box.
With proper assembly, the circuit does not need to be additionally configured and the microphone can be immediately connected to work. This microphone amplifier greatly improves sound quality and there is no extraneous noise. The circuit also works well with an electret microphone.
Important! Before connecting the microphone to the device, you should check its contacts, and also that the power at the microphone input is at least 5 volts.
If there is no such voltage, then we take another plug and attach it to the connector and measure with a voltmeter the voltage that is between the large branch and the other two branches, which are shorter. When measuring voltage, you need to be careful that there is no shorting of the terminals of the plug to each other.
To check, we take a dynamic microphone, connect, connect through the wire the output of the amplifier and a computer or speakers, or to the device that you need and turn on the power. If an LED was used during assembly, then its glow indicates that the amplifier is working. But the electrode itself is not required in the circuit.
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