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Simple Circuit Audio Oscillator - As a piece of test equipment, an audio oscillator has to be considered essential for anyone working in with hi-fi gear. Together with an audio millivoltmeter (as described in Project 16) , and even better if you have access to an oscilloscope, you will be able to make proper measurements on everything from preamps, RIAA equalisation stages (for vinyl disks) , tone controls, crossover networks, etc __ Designed by Rod Elliott ESP
Simple Circuit Colour Organ - This is a simple, one lamp colour organ. It is far less complicated then the Three Channel Colour Organ. It is simply a lamp controlled by an SCR. It can be built in a few minutes, and combined with other circuits to make some pretty neat effects. __ Designed by Aaron Cake
Simple Circuit 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. You have probably seen this circuit before, it is fairly common. I have seen it in several __ Designed by Aaron Cake
Simple Circuit two line output combiner - Sometimes there is need to combine the output of two line level audio sources to be fed to one input. A standard way in professional audio is to use a mixing desk, but on home audio system you might want to look for a simpler and less expensive alternative. Some people have suggested of combining two audio outputs with an "Y-adapter" which is ment to split one output. Those adapters are just one male connector and two feamle connector directly wired to each other in the followin way: __ Designed by Tomi Engdahl
Sound Detector - for use with the sound detector circuit/electret mike amplifier. when the 555 IC goes into timing mode (triggered by an output signal from the sound detector amplifier,) the timer's output (pin 3) is set into HIGH for a duration set by C2, and R2. adjusting R1 will adjust how long it listens, from __ Designed by Andy Wilson
Sound Operated Switch - This sensitive sound operated switch can be used with a dynamic microphone insert as above, or be used with an electret (ECM) m`icrophone. If an ECM is used then R1 (shown dotted) will need to be included. A suitable value would be between 2.2k and 10kohms. The two BC109C transitors form an audio preamp, the gain of __ Designed by Andy Collison
Speaker Box Audio Amp - I did this design after getting a new computer. After buying the processor, monitor, and printer, I wasn't willing to spring for a set of speakers too. After going "soundless", I decided to add speakers. Of course, this was the perfect excuse warm up the soldering iron to try out a new design. This original design is a variation on a well-known design, examples of which can be found in a great many texts. My variation was to add a second differential stage to replace the usual common emitter-plus-constant current source. Doing so opens up a second inverse feedback path. __ Designed by Miles Prower
Speaker Microphone - This circuit takes an ordinary loudspeaker and allows it to be used in reverse, as a microphone. __ Designed by Andy Collison
Speaker Protection & Muting - Protect speakers from turn-on and turn-off transients and amplifier faults __ Designed by Rod Elliott ESP
Speaker Signals to Line Level Inputs - The circuit is designed to work with typical HIFI amplifiers where negative speaker connector (black) is connected to amplifier ground. Be careful here because some modern amps have both terminals actively driven. Connecting either one to a common reference could cause the output stage to smoke __ Designed by Tomi Engdahl
Speaker-Headphone Switch For Computers - If you need to use a headset with your PC, then you will know how frustrating it is continuously swapping over speaker and microphone cables. This is even worse if the PC is parked in a dark corner and the hard-to-read writing on the sound card sockets is covered in dust. This simple switch box|
Spring Reverb Unit for Guitar or Keyboards - A high performance spring reverb unit for guitar amps __ Designed by Rod Elliott ESP
Spyder an Eight Output Pedalboard Power Supply - Outputs regulated 9V DC __ Designed by R.G. Keen
Stereo Audio Distribution Buffer for Headphones - Most audio signal sources have only one stereo output, which means they can drive only a single pair of headphones with a resistance of around 32 ohms or a single line __ Electronics Projects for You
Stereo Broadcast Limiter - Circuit for the Ramsey FM10a/FM25 Transmitter __ Designed by G. Forrest Cook
Stereo Headphone Amplifier - Here is an inexpensive circuit for a stereo amplifier to drive a low-impedance headphone set. The circuit uses a few cheap transistors (BC547 and BC557) and passive components like resistors, diodes __ Electronics Projects for You
Stereo Headphone Amplifier - This is an improved version of headphone amplifier I've built many years ago. I wanted so much to share it with you because this simple circuit has done a great service|
Stereo LED VU meter using discrete components BC547 transistors - This is it. It's a STEREO LED LEVEL METER. It's the cheapest and best bar graph display available and best of all, it uses readily available components.
You only need a handful of LEDs, 22 transistors, some resistors, diodes and a set of electrosit doesn't require any chips __ Designed by Collin Mitchell
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
Studio Series Stereo Headphone Amplifier - A top-class unit for the audio enthusiast!__ SiliconChip
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 |
