Audio
Electronic Doorbell with Counter
Description
This circuit uses a synthesized sound chip from Holtek, the HT-2811. This reproduces the sound of a “ding-dong” chiming doorbell. Additionally, the circuit includes a CMOS 4026 counter display driver IC to count your visitors. More >
Telephone ringtone generator circuit
This is a simple home telephone ringtone generator circuit which is built with applying only several electronic components / parts. It generates simulated telephone ringtone and requires only DC supply with 4.5V DC to 12V DC voltage.
One may possibly use this circuit in ordinary intercom or phone-type intercom. The sound is pretty loud when this circuit is operated on +12V DC power supply. Even so, the volume of ring sound can be adjusted. More >
CAR-REVERSING HORN WITH FLASHER
Here is a simple circuit that starts playing the car horn whenever your car is in reverse gear. More >
Sound activated lights
This diy sound activated lights circuit turns a lamp ON for a short duration when the dog barks (or a relatively strong sound) giving an impression that the occupants have been alerted. More >
Headphone Amplifier with IR Communication
This low cost project can be used to reproduce an audio from TV without creating any disturbance from other people. More >
Mobile Car Stereo Player
Using a mobile phone while driving is dangerous. It is also against the law. However, you can use your mobile phone as a powerful music player with the help of a stereo power amplifier. This does away with the need of a sophisticated in-dash car music system. More >
Electric Guitar Preamplifier
Here is the circuit of a guitar preamplifier that would accept any standard guitar pickup. It is also versatile in that it has two signal outputs. More >
Wireless headphones receiver circuit
The wireless headphones receiver presented is an standard application of ZN415 produced by Ferranti ( short wave receiver). ZN415 assures a quality reproduction, has a 1.5 battery alimentation and contains a MA detector and audio amplifier.
Wireless headphones transmitter circuit
This wireless headphones transmitter assures a quality reception over 2 meters. The oscillator frequency is between 1750KHz and 3500KHz and for antenna we use a ferrite bar. IC1 amplifies the audio signal and TC1 is a buffer. D1 signals that the transmitter is on and is a voltage stabilizer for the oscillator . More >
Audio Voice-Over any other audio
This is a circuit where a microphone and preamp circuit (voice circuit) have priority over any other audio signal. You can think of this as a one way intercom, if the main amplifier is used for listening to music, then when the push to talk switch is pressed, the amplifier is switched to the voice signal. More >