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Audio circuits 
1KHz sinewave generator simple circuitry, low distortion, battery operated. Variable, low impedance output up to 1V RMS, 2 transistors
24 dB/Octave 2/3-Way Linkwitz-Riley electronic crossover
3 band equaliser Using a single op-amp this easy to make equalizer offers three ranges, low frequency,mid frequency,and high
60-Hz, High-Q notch filter This high-Q notch filter is based on the "Twin-T" design. It produces a very deep notch in the response curve at about 59.7 Hz. This is useful to remove 60-Hz hum and noise from audio recordings or live performances. Response is down over -60db at the center point, pdf file
8 Note Tune Player This neat little circuit can play 8 note tunes at any speed you want. You select the notes with 8 trim pots. The speed in selected through a ninth pot
Adjustable 60Hz Filter On this page three adjustable notch filters configurations are shown . They can be used in your small pre-amp or amplifier project to filter out any HUM at 50 Hz ( European ) or 60Hz
Adjustable Audio Notch Filter A variable notch filter with both high and low pass filters
Audio amplifier output relay delay the purpose of this circuit is to control the relay which turns on the speaker output relay in the audio amplifier. The idea of the circuit is wait around 5 seconds ofter the power up until the spakers are switched to the amplfier output to avoid annoying "thump" sound from the speakers
Audio circuits audio circuits,  2 Watt Amplifier  A low distortion amplifier using discrete components, ECM Mic Preamplifier A high quality preamp for electret mic inserts, Tone Controls, Stereo Line Driver, TDA2030 8 Watt amplifier, Audio Notch Filter For audio frequencies 100Hz - 10KHz, 6 Input Mixer 3 Mic inputs, 3 Line Inputs, Hi-Fi Pramplifier, Peak Reading Audio Level Meter, Doorphone Intercom
Audio compressor audio compressor circuit
Audio detector for starting robots
Audio level meter - analog audio level measurement circuit circuit
Audio pages (ESP) 60-100W power amplifier, preamp power supply, Hi-Fi phono (RIAA) preamp, 50W IC power amplifier, class A power amplifier, 300W subwoofer power amplifier, headphone amp, Linkwitz transform circuit, 20W/ch stereo IC power amp, test equipment, VU meter...
Audio notch filter audio frequencies 100Hz - 10KHz
Audio opamp circuits
Audio power meter LM3915, stereo VU meter, pdf file
Audio test oscillator audio test oscillator circuit
Audio VU meter LM324, This circuit uses two quad op-amps to form an eight LED audio level meter. The op-amp used in this particular circuit is the LM324
A weighting filter
Balanced microphone preamp with phantom power
Bat Detector Circuit
Bat Detector Circuit Bat Detector Circuit
Curious C-Beeper The Curious C-Beeper uses the two-transistor flasher in conjunction with a darlington transistor to make a most unusual capacitance beeper probe. When a capacitor is touched to the probe, the probe beeps at a frequency that varies with capacitance
Digital Volume Control
Doorphone intercom LM386
Electret Condenser Microphone amplifier microphone pre-amplifier for an Electret Condenser Microphone, pdf file
Full-duplex doorphone with 3 wires connection a two-way (full-duplex) construction planned for use as doorphone
High Q Notch Filter The twin ``T'' network is one of the few RC filter networks capable of providing an infinitely deep notch. By combining the twin ``T'' with an LM102 voltage follower, the usual drawbacks of the network are overcome, pdf file
LM3915 dot/bar display driver pdf file
Low impedance microphone amplifier a microphone amplifier for use with low impedance (~200 ohm) microphones, transistor, opamp
Microphone Amplifier with HF Decoupling
Microphone Circuit Test Oscillator
Music & special effects Electronic Canary, Metronome Circuit, Sound Effects Generator, Sound Effects Generator, Electronic Siren
Music to light modulator A music-to-light modulator is a circuit which controls the intensity of one or more lights in response to an audio input, MOC3021, pdf file
Negative feedback design for amplifiers how to modify a small class AB amplifier for low distortion and minimal power drain
One way intercom a simple one way intercom can be made by connecting an electret micrpohone to an LM386 amplifier chip, pdf file
Peak reading audio level meter CA3140, will indicate peak audio response on an analog meter
Reverse RIAA Equaliser How to use a needless phono input as a universal line input?
Siren circuit siren circuit with transistors
Siren circuit Emergency Siren Simulator, The heart of the circuit is the two transistor flasher with frequency modulation applied to the base of the first transistor, ...
Sound detector tone decoder NE567
Sound level indicator Sound level indicator, LM3915
Sound operated switch sound operated switch circuit
Sound operated switch sound operated switch circuit
Theremin the theremin is a musical instrument that uses electronic circuits to produce audible tones, having the unusual aspect of being controlled by the player's hand motions near the instrument's two "antennas," without the hands touching the instrument. One hand is used to control the theremin's pitch, and the other hand is used for controlling the volume, a tip
Tone detect with the NE567 Tone detection circuit with the NE567
Tone detection circuit with the NE567
Tone (pitch) display The heart of the circuit is the tone (pitch) display section, based on the popular LM3914 display driver, logarithmic scale, LM311 comparator, LM2917, Educypedia
Transformerless Balanced Line Driver with Floating Output
Transistor Organ This simple circuit can provide hours of enjoyment as you learn tunes, play duets or just make some really weird sounds by pushing all the buttons at once
Ultrasonic switch The circuit described generates (transmits) ultrasonic sound of frequency between 40 and 50 kHz. As with any other remote control system this cirucit comprises of a mini transmitter and a receiver circuit. Transmitter generates ultrasonic sound and the receiver senses ultrasonic sound from the transmitter and switches on a relay, schematics
Ultrasonic switch
Voice-over circuit
VU meter
VU meter A very simple circuit of indication of level, with 10 Leds
VU meter Stereo VU Meter circuit
VU meter Stereo VU Meter circuit
Wien-Bridge Oscillator 15Hz - 150kHz

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Last updated on: 2011-01-15 | Copyright © 2011-2013 Educypedia.