This circuit has a single input and 4 independent outputs, each amplified with an operational amplifier.

This metronome circuit with adjustable BPM, allows those persons who study or are music fans, to keep the timing, quite accurately for a long period of time.

4-channel audio mixer using LM3900 IC

4 operational amplifiers, some resistors and capacitors to implement an audio mixer with a very simple design.

6-LED VU meter using one transistor

This simple 6-LED VU meter allows us to visualize the level of an audio signal. Due to its few components, it is a cheap circuit and easy to build. Components are very common and very easy to obtain.

Music box circuit using a CD4017 decade counter and two 555 timers.

This circuit attempts to emulate the operation of a music box. The maximum number of notes is 10, allowing us to make a simple melody.

TDA2822M 2 watt audio amplifier circuit

This 2 watt audio amplifier circuit is specially designed to consume little power and to be used with batteries or low voltage power sources.

8 LED VU meter made of IC-LM324.

This circuit can be used to display the variation of an audio signal in a group of 8 LEDs, behaving like a VU meter. We could use an specific integrated circuit used for VU meters, but we decided to use a readily available integrated circuit: The LM324 op amp.

400 watts Stereo Amplifier Circuit using STK4050

This 400 watts stereo amplifier circuit uses the Sanyo STK4050 hybrid IC, a high quality low noise amplifier. Its maximum output power is 200W per channel

Tone generator using two 555 timers

This circuit uses the well-known 555 integrated circuit to generate a range of sounds that are heard through a small loudspeaker.

Audio level indicator circuit using LM339

This audio level indicator is very interesting because it allows us to visualize the audio level intensity by connecting this circuit to the input of a loudspeaker.

Microphone Mixer using operational amplifiers

This Microphone Mixer combines signals from 3 different sources (3 microphones) easily and economically.

6 Watts Audio Amplifier Circuit with TDA2613 (Hi-Fi)

High fidelity 6 watts audio amplifier circuit with the TDA2613 Integrated Circuit, very easy to implement due to its very few external components