2 Channel Noise Gate:  (circuit added 7/02)

2 Line Mixer:  (schematic / circuit added 9/06)

2 Line Output Combiner:  Convert consumer equipment stereo signal to mono or combine audio signal from two different equipments to1-input (added 4/02)

3 Level Audio Power Indicator:  Battery-operated3 LED display that connect it to loudspeaker output (added 9/04)

30 Ddm to +30 Ddm Audio Level Meter:  circuit with balanced input and adjustable gain to drive needle type VU meter, uses special amplifier module from Op-Amp Labs (added 4/02)

300 Watt Subwoofer Power Amplifier:  (schematic added 9/02)

6 Headphone Splitter:  (circuit added 9/06)

Active Sub-Woofer and Controller:  (electronic circuit added 2/07)

Active Subwoofer and Controller:  (schematic added 9/02)

Add on Stereo Channel Selector:  (electronic Circuit / Schematic added 10/04)

Amplified Ear:  (circuit added 9/04)

Amplifier Phono Input as Line Level Input:  (electronic schematic added 8/02)

Amplifier Thermal Protection:  (schematic added 9/02)

Analog Synth Keyboard Schematic:  (electronic circuit added 2/07)

Anit Riaequalizer for Line to Mag Phono Converter:  (electronic schematic added 8/02)

Arc welder sound simulator:  (diagram added 2/07)

Audio Amp Output Power Limiter:  (schematic added 9/02)

Audio Amp Timer:  Turns-off your amplifier when idle for15 minutes Fed by amplifier tape-output (added 9/04)

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 Auto Shutoff:  purpose of this circuit is to automatically turn off any device plugged into its power outlets after a certain period of Time of silence (added 4/02)

Audio Auto-Shutoff:  (circuit added 10/06)

Audio Detector Circuit:  (diagram added 2/07)

Audio graphic equaliser:  (diagram added 2/07)

Audio Level Meter:  (schematic added 9/02)

Audio Line Isolator #1:  (electronic circuit added 1/03)

Audio Line Isolator #2:  (electronic schematic added 8/02)

Audio line isolator:  (electronic circuit added 2/07)

Audio mixer:  (diagram added 2/07)

Audio notch filer:  (electronic circuit added 2/07)

Audio Peak Reading Meters:  (circuit added 7/02)

Audio Signal Source:  (diagram added 2/07)

Audio Transformer #2:  notes on using audio transformers for balanced signal interfacing (added 4/02)

Audio VU Meter:  (schematic / circuit design added 9/02)

Auto Shut-Off for Cassette Players and Amplifiers:  (electronic Circuit / Schematic added 10/04)

Automatic Charger for Battery Operated Hi-Fi Preamps:  (circuit diagram added 2/07)

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

Balanced Audio Input Circuit:  109KB PDF file (added 4/02)

Balanced Line Driver & Receiver:  (diagram added 2/07)

Bass Beat Extractor:  an automatic gain control circuit followed by a low pass filter, converts  beat into a sharp pulse suitable for triggering  strobe or chaser (added 4/02)

Bluetooth Headset:  Intersil Application Block Diagram  (app note added 6/06)

Bridging Adapter for Power Amplifiers:  (schematic / circuit design added 9/02)