Stereo Tone Control with Line In + Microphone Mixer

This is an active stereo tone control circuit using very well known op-amp IC of TL072. The circuit include mic pre-amp and mixer control. In this design, we have two inputs: one for line (stereo), one for microphone and has control of the three audio frequency (high/treble, medium and low/bass). It also provide balance control… Read More »

Uninterruptible Power Supply with PIC17C43 Microcontroller

This is a MicroChip Uninterruptible Power Supply (UPS) reference design with PIC17C43 microcontroller. The document is available to download from the end of this post. At times, power from a wall socket is neither clean nor uninterruptible. Many abnormalities such as blackouts, brownouts, spikes, surges, and noise can occur. Under the best conditions, power interruptions… Read More »

Tube Mic Pre-Amp

The following diagram is the circuit diagram of tube mic pre amplifier 12AX7. This circuit is little hard to built. You must have an intermediate or advanced skills to build this circuit. All capacitors with value of 33uF are 16V, while the all others are 50V unless marked otherwise. Resistors marked with “#” are 1%… Read More »

Mic Compressor

Below is a mic compressor circuit that uses transistors as active components. VR1 and VR 2 is used to control the tone from the microphone, while VR3 and VR4 strengthening works to control the audio signal in the compressor mic. C10 must be used in this circuit. The circuit I got from my local computer… Read More »

Dynamic Microphone Amplifier

Here is the dynamic microphone amplifier circuit diagram. This circuit should be perfect for dynamic microphone… Dynamic microphones are versatile and ideal for general-purpose use. They use a simple design with few moving parts. They are relatively sturdy and resilient to rough handling. They are also better suited to handling high volume levels, such as… Read More »

Low Noise Portable Mic Preamp

This is the circuit diagram of portable mic preamp. This circuit consumes low current supply (about 2mA), so will have a long battery life for supplying the circuit. Harmonic distortion is about 0.1% @ 1V RMS output for all frequencies. Maximum input voltage (level control cursor set at maximum) = 25mV RMS. Maximum input voltage… Read More »

Low Impedance Microphone Amplifier

This is the circuit diagram of low impedance microphone amplifier. The circuit designed for use with low impedance (~200 ohm) microphones. It will work with regulated voltages between 6-30VDC. If you don’t build the impedance adapter part with T1, you get a microphone amplifier circuit for higher impedance microphones. In this case, you should directly… Read More »