Simple Circuit Surround Sound Decoder - This surround-sound decoder is based on the "Hafler" principle, first discovered by David Hafler sometime in the early 1970s. The original idea was to connect a pair of speakers as shown in Figure 1, for use as the rear speakers in the surround setup __ Designed by Rod Elliott ESP
Simple FM Stereo Tuner - This is one of my favorite radio builds just because of how simple it is and how well it is able to pick up a lot of FM radio stations. I have browsed the world in search of a one transistor FM receiver. I have seen a couple but they were always attached to some sort of added device, such as another IC or another transistor for amplification in the receiver itself.
Smooth Tone Clickless CW SideTone Generator - This circuit is about as good as it gets for generating morse code tones. It may be used as a code practice oscillator, a tone generator for a keyer, a sidetone oscillator for a CW transmitter or an audio Modulated CW (MCW) generator for an FM transmitter or repeater __ Designed by G. Forrest Cook
Soft Switching Amplifier with Tone Controls - Built around an LM380, this amplifier includes tone controls and electronic "soft switching". The soft switching circuitry ensures power is built up gradually eliminating the dc thump __ Designed by Andy Collison
Sound Level Indicator - This project uses an LM3915 bar-graph IC driving two sets of ten LEDs for a 30dB range. The circuit is unique because it has an additional range of 20dB provided by an automatic gain control to allow it to be very sensitive to low sound levels but it increases its range 20dB for loud sounds. __ Designed by Audioguru
Stereo Test Tone Generator - This circuit produces two audio frequency sine waves with different frequencies but equal amplitudes. It can be used for testing a variety of stereo audio equipment. The circuit was originally developed the purpose of aligning an FM Stereo Modulator, like the type used in low power FM stereo transmitters. Two tone outputs are available, the low tone has a secondary output that is 180 degrees out of phase with the primary output. The circuit is also handy for testing computer sound card inputs. A variety of waveform configurations can be produced by plugging a stereo audio patch cord into the four output jacks. __ Designed by G. Forrest Cook
Stereo Tone Control Based LM1036N - The following circuit is a Stereo Tone Control Circuit which build based LM1036N. The LM1036 works as a DC controlled tone (bass/treble), volume and balance circuit for stereo audio purposes in car radio, TV and audio systems. An extra control input will allow loudness compensation to be simply effected. Four control inputs provide control of the bass, treble, balance and volume capabilities through application of DC voltages from a remote control system or, additionally, from four potentiometers that might be biased from a zener regulated supply given on the circuit. Each tone response is defined by a single capacitor selected to give the desired characteristic.
Stereo Tone Control with Transistor - Above diagram is the circuit diagram of stereo tone control which also available to buy in kit, you could possibly look for the kit at electronic part store close to your location. The tone control require 12v of power supply to work.
Stereo Width Controllers - Sometimes, for a variety of reasons, it would be nice to vary the width of the 'sound stage' when listening to stereo recordings. Although technically this is anything but hi-fi, it is a useful addition to PC speakers, or even for the music centre in the listening room. __ Designed by Rod Elliott ESP
Subwoofer Equaliser - The Linkwitz transform circuit is a hugely flexible way to equalize the bottom end of a sealed loudspeaker enclosure. A speaker that is corrected using this method is flat from below resonance to the upper limit of the selected driver. The low frequency roll off point is determined by the parameters of the transform circuit __ Designed by Rod Elliott ESP
Surround Sound Decoder - This surround-sound decoder is based on the "Hafler" principle, first discovered by David Hafler sometime in the early 1970s. The original idea was to connect a pair of speakers as shown in Figure 1, for use as the rear speakers in the surround setup __ Designed by Rod Elliott ESP