DIY phantom power for microphone

Phantom power is a way of simultaneously transmitting information and power voltage across the same elements. Most often used in audio systems. Specifically, in microphones.

What is phantom power for a microphone?

Basically, this method of transmitting information is used in condenser microphones. Thanks to phantom power, microphones provide high-quality and natural sound, as well as provide greater sensitivity.

DIY phantom power for microphone

Often in the design of sound technical devices (for example, amplifiers and preamps), it is necessary to include a phantom power unit in the structural circuit. It is needed to power the microphone, and its main characteristics are noise filtering and stability. The basis for this block will be the multiplier circuit, on diodes and capacitors. For audio devices, multiply by 4.

As can be seen from the diagram, the multiplier is powered by a transformer Tr1. Then the capacitors C1-C4 and the diodes VD1-VD4 form a four-fold multiplier. The load of the multiplier is an RC filter (R1C5 and R2C6). After them, another was added. But the already active filter is LM317. In addition to the filtering function, it also performs voltage stabilization. After the filter, capacitor C7 is connected to the circuit to prevent self-excitation of the circuit. Without this element, there is a risk of creating your own noise at the circuit output.

You should also say a few words about the remaining elements of the scheme.

R5 is a resistor with variable resistance that regulates the output voltage. It is necessary so that the user can manually set the values ​​at which the background will be minimal and the voltage maximum.

ATTENTION. Resistors R3, R4 and R5 can be very hot, so they should be taken at least 0.25-0.5 W in power.

VD5 is a zener diode that protects the amplification stage from a voltage drop during charge of C7 or during incorrect adjustment of R5. This element protects the circuit from failure if its reverse voltage is not more than 35V.

Watch the video: How To: Scratch Build 48V Phantom Power Supply For Condenser Mic's (March 2024).

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