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Speaker Protector Circuit – Circuit Schematic
Speaker Protector Circuit
Most of the transistors in this speaker protector function as switches. Normally, Q4, Q5, and K1 are on and the speakers are connected to the amplifier. Howeve...
Precision Audio-Frequency Generator Circuit – Circuit Schematic
Precision Audio-Frequency Generator Circuit
The precision audio-frequency-generator consists of several sub circuitsan audio-amplifier/filter circuit, an automatic level control, a variable voltage-contr...
Receiver Af Noise Limiter For Low-Level Signals Circuit – Circuit Schematic
Receiver Af Noise Limiter For Low-Level Signals Circuit
A preamplifier in the audio frequency range amplifies a noisy audio signal to drive a diode clipper. ...
Amplified Noise Limiter For Sw Receivers Circuit – Circuit Schematic
Amplified Noise Limiter For Sw Receivers Circuit
The noise limiter circuit has a preamplifier clipper, and a switchable audio bandpass filter. Audio levels in the 5- to 50-mV range are amplified in a preamp t...
Audio Dynamic Noise-Reduction System Circuit – Circuit Schematic
Audio Dynamic Noise-Reduction System Circuit
Ul is a dedicated IC (National Semiconductor) that achieves up to 10 dB noise, reduction by an adaptive bandwidth scheme ...
Melody Circuit Circuit – Circuit Schematic
Melody Circuit Circuit
A high-quality melody circuit. The slow decay waveform produced will create chime-like notes. Pitch, tempo,...
Musical Instrument Digital Interface (Midi) Transmitter Circuit – Circuit Schematic
Musical Instrument Digital Interface (Midi) Transmitter Circuit
Used for digital control of musical instruments, this transmitter converts the digital data signals to equivalent optical signals for fiberoptic cable interfac...
Musical Instrument Digital Interface (Midi) Receiver Circuit – Circuit Schematic
Musical Instrument Digital Interface (Midi) Receiver Circuit
Receiver photodiode SFH250 is used to convert optical data pulses at 32.5 Kb to electrical signals. Buffer T2 feeds the signals to cascade amplifier T3-T4, the...
Precision Audio Generator For Musical Instrument Tune-Up Circuit – Circuit Schematic
Precision Audio Generator For Musical Instrument Tune-Up Circuit
One section of the precision audio frequency generator uses an electret microphone element to pick up audio from the piano. That signal is then processed and s...
Bird Feeder Monitor Circuit – Circuit Schematic
Bird Feeder Monitor Circuit
The first amplifier circuit is a bird phone. In this circuit, the electret mike (MIC1) is mounted in the neck of a large plastic funnel. The amplifier, built a...
Baby Monitor Circuit – Circuit Schematic
Baby Monitor Circuit
Transmitter operation. Operating power for the transmitter circuit is derived directly from the ac line. The dc power to operate the circuit is generated in tw...
Unity-Gain Four-Input Audio Mixer Circuit – Circuit Schematic
Unity-Gain Four-Input Audio Mixer Circuit
The circuit has four inputs. The voltage gain between each input and the output is held at unity by the relative values of the 470kH input resistor...
Fet Microphone Mixer Circuit – Circuit Schematic
Fet Microphone Mixer Circuit
A JFET transistor-is used as a high-to-low impedance converter and signal mixer. Input impedance is approximately 50.0 kQ but it can be increased by increasing...
Audio Mixer Circuit – Circuit Schematic
Audio Mixer Circuit
Designed around an LM3900 quad op amp, this mixer combines 2-line and 2-mike inputs and sums them at the output terminal. ...
Low Noise 4 Channel Guitar Mixer Circuit – Circuit Schematic
Low Noise 4 Channel Guitar Mixer Circuit
ICl-a, ICl-b, IC2-a, and IC2-b all function with a gain of about 19. Their outputs are mixed via the level-control pots and the resulting signal amplified by I...
Octave Equalizer Circuit – Circuit Schematic
Octave Equalizer Circuit
This circuit is one section of an octave equalizer used in audio systems. The table shows the values of CI and C2 that are needed to achieve the given center f...
Af Drive Indicator Circuit – Circuit Schematic
Af Drive Indicator Circuit
This circuit was used with an audio power amplifier to detect the point at which output is -3 dB from maximum, indicated by LED D5, and at clipping, shown by L...
Acoustic Field Generator Circuit – Circuit Schematic
Acoustic Field Generator Circuit
Referring to the simplified schematic in A, the AFG is made up of 10 relatively simple circuit elements. ICl-c and ICl-d arc configured as unity-gain noninvert...
Audio Limiter Circuit – Circuit Schematic
Audio Limiter Circuit
An optoisolator is used as an attenuator in this circuit. When the LM386 draws more current on audio signals, the 2N3638 turns on, which biases the optoisolato...
Radio Commercial Zapper Circuit – Circuit Schematic
Radio Commercial Zapper Circuit
The LR inputs are summed, dated and drive a comparator. The comparator senses level and generates a transition when audio inputs go above or below preset thres...