Misc audio

1. 120 Second Message Recorder (PDF)
2. 3 Channel Spectrum Analyzer
3. 40 Second Message Recorder (PDF)
4. 6 Input Mixer
5. 90/120 Second Message Recorder (PDF)
6. A-B Switch Box For Amplifier Comparisons
7. ABX Double Blind Audio Tester
8. Active Sub-Woofer and Controller
9. Amplifier Thermal Protection
10. Amplifier Timer
11. Audio Auto Shutoff
12. Audio Distribution Amplifier
13. Audio LED VU meter
14. Audio Level Meter
15. Audio Level Meter (vumeter)
16. Audio Level Meter 3
17. Audio Light Modulator
18. Audio Line Driver
19. Audio Mixer
20. Audio Mixer - Transistorized
21. Audio Output Level Indicator
22. Audio Signal Source
23. Audio VU Meter
24. Automatic Fader
25. Bat detector microphone pre-amplifiers
26. Balanced Line Driver
27. Bass-treble tone control circuit
28. Bass Booster
29. Beeper
30. Better Volume Controls
31. Bias circuit
32. Bridging Adapter For Power Amplifiers
33. Build a Microphone Polarity Tester
34. Build a Tape Linearizer and a Distortion Analyzer
35. Building the L-R Test Set
36. Classic Audio Mixer
37. Classic Fuzz
38. Classic Fuzz / Booster
39. Compressor
40. Compressor 2
41. Connecting speaker signals to line level inputs
42. Ducker Plus
43. Digital Delay Unit For Surround Sound
44. Digital Echo Unit
45. Digital Volume Control
46. Direct Injection Box for Recording
47. DISPLAYER - Theory and Construction
48. Distortion (MXR)
49. Ear Lobe Pulse Device (PDF)
50. Equalizer - 10 Band equalizer
51. Equalizer - 3 Band graphic equalizer
52. Equalizer - 5 Band graphic equalizer
53. Equalizer - Audio Graphic Equaliser
54. Equalizer - Eight Band Sub-Woofer Graphic Equaliser
55. Equalizer - Expandable Graphic Equaliser
56. Equalizer - Five Band graphic equalizer
57. Equalizer - Mono Audio Equalizer
58. Equalizer - Parametric And Sub-Woofer Equaliser
59. Equalizer - Subwoofer Equaliser
60. Equalizer - 50,200, 800, 1600Hz, ...
61. Electronic Canary
62. EPROM Sequencer
63. Factory Siren
64. Fader - Mono
65. Fast Audio Peak Limiter
66. FET Audio Mixer
67. Guitar and Bass Sustain Unit
68. Harmonic distortion detector
69. Hornet - Fuzz Box
70. Improved PL Tone Encoder
71. Isolator transformer for audio lines
72. Jednostavna mikseta
73. JORDAN BossTone
74. LED Audio VU Meter
75. Line level signal to microphone input adapter
76. Linkwitz Cosine Burst Generator
77. Linkwitz-Riley Electronic Crossover
78. Load Sensing Automatic Switch
79. Loudspeaker Protection and Muting
80. Melody generator for greeting cards
81. Metronome Circuit
82. Microphone Mixer
83. Midi Cable Optoinsulated
84. Mini Compressor
85. MIKSETA
86. Mini Audio Analyzer
87. Mini Mixer
88. Mono VU-Meter I
89. Mono VU-Meter II
90. Music Box Engine (PDF)
91. Peak Reading Audio Level Meter
92. Power Amplifier Clipping Indicator
93. Signal Detecting Auto Power-On Unit
94. Room Noise Detector
95. S/PDIF Digital to Analogue Converter
96. Simple AGC System
97. Simple electronic buzzer
98. Simple Surround Sound Decoder
99. Simple two line output combiner
100. Simplest Ever Amplifier Bridging
101. Six-channel Mixer and Amplifier
102. Sound detector latch
103. Sound detector tone decoder
104. Spectrum Analyzer and Equalizer Designs
105. Stereo Channel Selector
106. Stereo Compressor (PDF)
107. Stereo Limiter
108. Stereo Mixer
109. Stereo Tone Control
110. Stereo VU Meter
111. Stereo Width Controllers
112. Surround Sound Decoder
113. Surround Sound Decoder 2
114. Three-Level Audio Power Indicator
115. Tone Control
116. Tone Control 2
117. Tremolo
118. Use One Pot to Control Two Channels
119. Variable Amplifier Impedance
120. VERY LOUD BEEPER CIRCUIT (PDF)
121. Visual Metronome
122. Voice Record - Playback
123. Voice Scrambler
124. VU Meter 1
125. VU Meter 2
126. VU Meter 3
127. VU Meter 4
128. VU Meter 5 with UAA180
129. VU Meter 6
130. VU Meter 7
131. VU Meter 8
132. VU Meter 9
133. VU Meter 10 with AN6884 (PDF)
134. VU METER AMPLIFIER
135. VU Stereo Meter
136. VU And PPM Audio Metering
137. VU-metar sa komparatorima
138. VU-metar sa tranzistorima
139. Warbler siren
140. Wah Wah
141. Wah 2