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 the Pioneer D500). It was tested by Dr. Horst Ludwig with the Sony DTC-55 and 57 and it works with my Sony DTC-670. Chances are good that it will work in other 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 7/06)

Simple Amplifier:  (electronic circuit added 7/03)

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

Single Chip 50 Watt/8 Ohm Power Amplifier #2:  Uses LM3876 HiFi amplifier IC from National Semiconductor (added 4/02)

Single Chip 50 Watt/8 Ohm Power Amplifier:  Uses National Semiconductor LM3876 Power IC. Voltage gain is 27dB.  Voltage gain is 27dB as shown, but this can be changed by using a different value resistor for the feedback path (R3, currently 22k, between pins 3 and 9). The inductor consists of 10 turns of 0.4mm enameled copper wire, wound around the body of the 10 Ohm resistor. The insulation must be scraped off each end and the wire is soldered to the ends of the resistor. (added 10/05)

Single Ended Class A2 Sv81110 Stereo Amp:  (diagram added 6/03)

Small Amplifier Circuit:  Uses many amplifier ICs, from feWatt-Watts to200-Watt (added 4/02)

Soft Start Circuit for Power Amps:  (diagram added 6/03)

Spatial Distortion Reduction Headphone Amp:  (diagram added 6/03)

Speaker Microphone:  (schematic / circuit design added 9/02)

Stereo Jack Adds No-Cost Power/Logic Control:  04/15/99 EDN-Design Ideas / (added 11/05) [Note:  File contains multiple circuits.  Scroll to find this one]  Many battery-powered devices use peripherals that require only two conductors to complete their interfaces. You can use stereo phone jacks and monaural plugs to perform poweror logic-control functions in addition to completing their required I/O connections. Monaural plugs short-circuit the ring and sleeve of stereo jacks. You can place the ring connector, normally considered a redundant ground return, into service as an spst switch. A simple wireless transceiver illustrates how you can use stereo jacks for switching with monaural plugs, stereo plugs, or both (Figure 1 and Figure 2). Using the design in Figure 1, you can connect the battery return to the ring of stereo jacks serving one or more I/O devices. The circuit in Figure 2 connects the returns of individual circuits to the ring....

Stereo Line Driver:  Power Amp Stereo Line Driver (added 4/02)

Stereo Tube Amplifier:  (circuit added 7/02)

Subwoofer Equalizer:  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. Should the enclosure size be too small and cause a lump in the response before roll off, this is also corrected. A conventional active crossover network is then used to divide the subwoofer signal from the main channel signals. Note that there is also a separate spreadsheet calculator available for calculating component values for different situations not handled by the original circuit. (added 7/03)

Tda2030 8 Watt Amplifier:  (schematic / circuit design added 9/02)

Thermofan to Keep Your Amp Cool:  (diagram added 6/03)

Three Transistor Audio Amp (50 Milliwatt ):  Here is a little audio amplifier similar to what you might find in a small transistor radio. (added 4/02)

TPA3001d1EVM Evaluation Module:  The TPA3001D1 is a 20-W mono Class-D audio power amplifier designed for 12V to 18V applications with a 4to 8-Ohm minimum speaker impedance. The efficient Class-D operation reduces solution size and cost by eliminating the need for heat sinks. In addition, integrated gain settings and surface mount packaging also help reduce the solution size. Designers can quickly evaluate the sound quality and verify specifications in their application with the TPA3001D1EVM.  (added 3/05)

TPA3007d1 Evaluation Module:  The TPA3007D1 is a 6.5-W mono Class-D audio power amplifier designed for 8V to 18V applications with an 8-W minimum speaker impedance. The efficient Class-D operation reduces solution size and cost by eliminating the need for heat sinks. In addition, integrated gain settings and surface mount packaging also help reduce the solution size. (added 3/05)

Tube Amplifiers:  (schematic / circuit design added 9/02)

Tube Buffer for CD Player:  (circuit added 7/02)

Two Watt Amplifier:  (schematic / circuit design added 9/02)

Voltage Controlled Amplifier:  (electronic circuit added 7/03)

Weighting Filter for Audio Measurements:  (schematic / circuit design added 9/02)