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AUDIO AMP + 3KHz FILTER
This circuit is the audio amp section for a complete optical transmitter.
The circuit amplifies and filters the voice audio signals from an electret microphone.
The circuit is described in more detail in the receiver section of Dave Johnson's
Handbook of Optical Through the Air Communications.
Links to electronic circuits,
electronic schematics, designs for engineers, hobbyists, students & inventors:
Audio Amp + 3khz Filter - This circuit is the audio amp section for a complete
optical transmitter. The circuit amplifies and filters the voice audio
signals from an electret microphone. The circuit is described in more detail in
the receiver section of Dave Johnson's Handbook of Optical Through the Air
Communications. (this link is off-site.) ….(designed by David A. Johnson)
Audio Amplifier - This simple amplifier shows the LM386 in a high-gain
configuration (A = 200). For a maximum gain of only 20, leave out the 10 uF connected
from pin 1 to pin 8. Maximum gains between 20 and 200 may be realized by
...(electronic design added 7/08)
Audio Amplifier for PC - This is an audio Amplifier that it has MULTIinputs for
MULTImedia use :-) (added 10/05)
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 .... (added 11/05)
Audio Indicator - This circuit can be used to remotely monitor a loudspeaker,
alarm, or audio source for presence of an audio waveform. It can also be directly
connected across loudspeaker terminals used as a peak indicator.
Audio Level Control Device - An automatic controlling device for sound levels
implements the steps of: installing a 10 digit 7-segment on the noise measurement
machine; controlling the Micom profit amplifier if an audio key was input into the
Micom (added 6/07)
Audio Level Meter - The circuit has a flat frequency response from about 20Hz to
well over 50Khz. Input sensitivity is 100mV for a full scale deflection on a 100uA
meter. Built on two common emitter amplifiers, the first stage has a preset resistor
which may be adjusted for a FSD. The last stage is biased to operate at roughly half
the supply voltage for maximum ac voltage swing. Audio frequencies are passed through
the 10u dc blocking capacitor and the full wave bridge rectifier converts the signal
to a varying dc voltage....(schematic design added 6/07)
Audio Level Meter VU Meter - This circuit uses just one IC and a very few number
of external components. It displays audio level in terms of 10 LEDs. The input
voltage can vary from 12V to 20V, but suggested voltage is 12V. The LM3915 is a
monolithic integrated circuit that senses analog voltage levels and drives ten LEDs
providing a logarithmic 3 dB/step analog display. LED current drive is regulated and
programmable, eliminating need for current limiting resistors…. (added
10/05)
Audio Light Modulator - Audio light modulations add to enjoyment of music
during functions organised at home or outdoors. Presented here is one such simple
circuit in which light is modulated using a small fraction of audio output from
speaker terminals of audio amplifier. The output from speaker terminals of
audio amplifier is connected to a transformer.... (added 10/05)
Audio Phase-Shift Oscillator with Amplitude Stabilization - Here is a phase-shift
audio oscillator with excellent distortion characteristics thanks to "softened" diode
limiting provided by the 1N914 and resistor divider and degenerated gain provided by
the 68 ohm emitter resistor. For minimum distortion….(added 05/05/05)
Audio Refinement Complete integrated amplifier - The Complete' is made to design
by Yves-Bernard Andre (YBA). My unit s/n is an early 00026, probably later copies are
different from the first batch. I used the amp for two years, and the only reason to
dig inside it - apart from 'how they did it' curiosity, was to disconnect the volume
pot motor. It returns to zero at each power down...(added 04/05/06)
Audio Spectrum Monitor - A digital audio signal processing experiment of real-time
FFT (Fast Fourier Transform) analysis. (added 10/05)
Audio Visual Indicator for Telephones - Many a times one needs an extra telephone
ringer in an ad joining room to know if re is an incoming call. For example, if
telephone is installed in drawing room you may need an extra ringer in
bedroom. All that needs to be done is to connect given circuit in parallel with
existing telephone lines using twin flexible wires. This circuit does not require any
external power source.... (added 10/05)
Audio Volume Relay Attenuator with IR Control - The circuit provides both audio
volume and input channel selection. A stepwise volume control is implemented with a
set of small relays and resistors. In a high-end audio system, a noticable sound
improvement over potentiomeneters can be obtained, also over 'audio grade'....(circuit
added 07/07/07)
Audison LR604XR amplifier (Car Audio) - Of the few car amplifiers I tested,
gutted, decyphered and fixed, this one seems to be the best in design quality. Too
many car amps (although solidly built) are apparently designed by computer class
students - too many traces, too many vias, absolutely wrong component placement etc.
And on schematic level...(added 04/05/06)
