Audio VU Meter - A VU meter with 20 LED's. The input source can be a line input or a microphone. . . [by P.
Townshend - EduTek Ltd]
Audio VU Meter - LM324, This circuit uses two quad op-amps to form an eight LED audio level meter. The
op-amp used in this particular circuit is the LM324. . . [by Matthew Hewson]
Audio VU meter 9 leds - 5 LED VU Meter kit is based on LB1409 IC from SANYO, which will indicates the volume level
of the audio signal it senses. . . [by IQ Technologies Industry, unless otherwise noted online]
Decibel Meter - The circuit below responds to sound pressure levels from about 60 to 70 dB. The sound is
picked up by an 8 ohm speaker, Amplified by a transistor stage and one LM324 op-amp section. You can also use
a dynamic microphone but I found the speaker was more sensitive. The remaining 3 sections of the LM324 quad
op-amp are used as. . . [by Bill Bowden]
Digital volume control - This digital volume control has no pot to wear out and introduces almost no noise in the
circuit. Instead, the volume is controlled by pressing UP and DOWN buttons. This simple circuit would be a
great touch to any home audio project. . . . [Design by Aaron Cake]
Digital volume control - Circuit of a digital volume control using six discrete ICs, including a 5V regulator, is
presented. IC1 (555) is configured to function as astable flip-flop. Its frequency or period may be adjusted
by proper choice of resistors R44, R45 and capacitor C6 combination. Here it is for 0. 3 second period. . .
[by IQ Technologies Industry, unless otherwise noted online]
Digital Volume Control - This circuit could be used for replacing your manual volume control in a stereo Amplifier.
In this circuit, push-to-on switch S1 controls the forward (volume increase) operation of both channels while
a similar switch S2 controls. . .
Volume Control Circuit - The heart of this digital
volume controller DVC circuit is IC2 4067, 16-channel analog multiplexer. Because the 1kΩ has been connected
between every input and output, the multiplexer can act like a potentiometer. The total resistance is 15kΩ.
You can use different values for the resistor to obtain a different characteristic. . . . [Circuit posted by
volume control has log taper - 11-Apr-02 EDN Design
Idea Digital potentiometers provide a compact and convenient way to attenuate audio-amplifier signals.
However, most such potentiometers suffer from at least one flawa nonlogarithmic step increment. To avoid this
problem, a user must . . . [by Doug Farrar, Los Altos, CA]
Digital Volume Control using DS1669
Digital Pot IC - This digital volume control has no
pot to wear out and introduces almost no noise in the circuit. Instead, the volume is controlled by pressing
UP and DOWN buttons. This simple circuit would be a great touch to any home audio project. . . . [by Aaron
High Resistance Voltmeter - This circuit is designed to provide an inexpensive way to to create a High Impedance
Voltmeter while making use of an inexpensive analog or digital multimeter. The circuit is specifically
designed for testing phototransistors when they are used in the circuits shown at this site. It has a very
high input impedance that will not "Load Down" the sensor that is being checked. . . . [Rob Paisley]
High-resolution volume-unit meter simplifies CD recording - 06/21/01 EDN Design Idea Digitally recorded music on CDs offers superior quality to that
recorded on vinyl records or tape, but most prerecorded CDs have an annoying characteristic: The average
volume levels of the recorded signal can vary by as much as 14 dB from disk to disk. S. . . [by Chester
Simpson, National Semiconductor, Santa Clara, CA]
LED Audio UV Monitor - The circuit is completely conventional, and is based on the App Note - from National
Semiconductor. The circuit is shown in Figure 1 and as you can see it uses a single IC and a few discrete
components. The extra diode (D3) is included to ensure that the DC to the LEDs is almost unfiltered. . .
[Rod Elliott (ESP)]
LEDs Indicate Sound
Level - 08/25/11 EDN Design Idea Build a
battery-operated portable meter to measure sound-pressure levels. This Design Idea describes a
battery-operated, portable soundlevel meter (Figure 1). Its portability makes it useful for detecting the
source of noise in automotive engines and power trains, factory machinery, and residential HVAC
(heating/ventilation/air-conditioning) systems. . . [by Stephen Kamichik, Ile Bizard, PQ, Canada]