A SCMS killer circuit:  This circuit was invented by Dr. Horst Ludwig from Germany and published in September 1992 in "Stereoplay", a German Hifi magazine. It's an additional board that should work with all DAT decks that have a Sony CXD2601 signal processor IC inside (many Sony DAT-decks and  Pioneer D500).

It was tested by Dr. Horst Ludwig with  Sony DTC-55 and 57 and it works with my Sony DTC-670. Chances are good that it will work in or decks with a CXD2601, but I'm not sure about that. (So I can't answer questions like "Will it work with my Sony DTC-59?"). Don't blame me if you ruin your deck. I don't even fully understand what this circuit does. (Maybe someone else could explain this!?) Modifications at your own risk!! ...   (circuit design added 10/06)

Active Subwoofer and Controller:  (electronic Circuit diagram added 03/03)

AM Radio PreAmplifier:  (circuit / schematic design added 6/06)

Amplifier:  (electronic circuit added 7/03)

AN-211: The Alexander Current-Feedback Audio Power Amplifier:  AN-211 Analog Devices Application Notes  (app note added 6/06)

AN-69: LM380 Power Audio Amplifier:  National Semiconductor Application Note   (app note added 2/06)

AN-79: IC PreAmplifier Challenges Choppers on Drift:  National Semiconductor Application Note   (app note added 6/06)

AN794: Power Considerations for the TC4864 Audio Power Amplifier:  Microchip Application Note Published 18-Jul-01   (app note added 2/06)

Audio Amp Based on LM383 8 Watts:  (circuit added 2/07)

Audio Amp Output Power Limiter:  (circuit diagram added 1/07)

Audio Amp Output Power Limiter:  (diagram added 6/03)

Audio Amp:  (circuit added 7/02)

Audio Amplifier Output Relay Delay:  This is a simple circuit which I built to one of my audio amplifier projects to control  speaker output relay. The purpose of this circuit is to control  relay which turns on  speaker output relay in  audio amplifier. The idea of  circuit is wait around 5 seconds after  power up until  speakers are switched to  amplifiers output to avoid annoying "thump" sound from  speakers. Anor feature of this circuit is that is disconnects  speaker immediately when  power in  amplifier is cut off, so avoiding sometimes nasty sounds when you turn  equipments off....  (added 11/05)

Audio Booster with 1 Transistor:  (circuit added 9/04)

Automatic Loudness Control:  Simple add-on module Switchable "Control-flat" option  (added 3/05)

AV (Audio/Video) Wireless Transmitter:  (electronic circuit added 4/05)

Balanced Low Noise Microphone Preamp:  very low noise, close to  oretical minimum, high hum rejection and variable gain with a single rotary pot, similar to that used in many professional grade mixing desks (added 4/02)

Bidirectional 2.4 GHz One Watt Amplifier:  (diagram added 6/03)

Bidirectional 900MHz One Watt Amplifier:  (diagram added 6/03)

Bridging Adapter for Power Amplifiers:  (electronic circuit added 7/03)

Brystom Power Amplifiers Circuit Diagrams:  (circuit added 7/02)

Car PreAmplifier and Artificial Earth:  (circuit / schematic design added 6/06)

Circuit Combines Power Supply and Audio Amplifier:  12/20/01 EDN-Design Ideas / (added 7/03) The circuit in Figure 1 can help if you must transfer dc power and audio over a pair of copper wires. One application for such a circuit is a low-cost door-opening system with speech input. The circuit uses only one IC, the well-known LM317, a low-cost power-supply regulator. Using this chip, you can....

Class D Audio Power Amplifiers:  01/04/01 EDN-Design Ideas / (added 8/03) -Class D amplifiers are much more efficient than other Classical amplifiers, but their high efficiency comes at the expense of increased noise and distortion. You can assess the frequencyand Time-domain characteristics of a Class D amplifier, including the output filter, using online simulations.

Class T Digital Audio Amplifier Evaluation Board:  This App Note describes a digital amplifier, which operates from13.5-Volt power source and outputs up to20W poor channel power. The App Note is in PDF format. Uses a Digital Power Processing Technology EB TA2020 from Tripath Technology. (added 4/02)

Compact 50W Integrated Amplifier with Meier Headphone Section:  (electronic circuit added 2/07)

Computer Microphone:  adapting electret microphone to soundcards with dynamic microphone inputs (added 5/02)

Crest Audio LT Series LT100 LT1500 and Lt2000 SchematIC Set:  A commercial Class D Amplifier, complete schematics in PDF format. (added 4/02)

Death of Zen (Doz) a New Class a Power Amp:  (schematic / circuit design added 9/02)

Direct Injection Box for Recording and Psystems:  (electronic circuit added 7/03)

Dual Phantom Power Pre-Amp:  (circuit / schematic design added 6/06)

ECM MIC PreAmplifier:  (schematic / circuit design added 9/02)

El Cheapo a Really Simple Power Amplifier:  (diagram added 6/03)

Five Tube Stereo Amplifier:  (circuit added 2/07)