Detailed entries for one subject from the INDEX TO HOW TO DO IT INFORMATION.
Click on a see also (sa) or tracing (xx) to view detailed entries about a related subject.
The entries are in alphabetical order by magazine name and then in chronological sequence.
To obtain a copy of any magazine article contact your local public library or the publisher.

Sound level meter consists of an AC VTVM, a microphone cartridge and this simple circuit.
AUDIO AMATEUR 3/1975 [Jan 1976] (v.6#3) pg. 28

A direct-reading sound meter responds to 40- to 10,000 cps and it can measure the intensity of sound up to 144 decibels. Est. cost: $25.
ELECTRONICS ILLUSTRATED Mar 1971 (v.14#2) pg. 27

The Rabbit Ear is hooked between your headphones and an amplifier. When room noise above a preset level is detected, the Rabbit Ear cuts into your headphones and lets you listen to whatever it's picking up.
HANDS-ON ELECTRONICS Mar-Apr 1986 (v.3#2) pg. 87

Unusual uses for solid-state piezo-transducers. (1) Fixed-frequency generator circuit. (2) Sound-activated decoder circuit. (3) Low-frequency crystal filter circuit. (4) Tone encoder/decoder circuit.
HANDS-ON ELECTRONICS Jan 1989 (v.6#1) pg. 84

Look at that sound. Transform the sounds of earthquakes, handclaps, etc. into photographs using an oscilloscope and a Cromemco D+7A A/D converter.
MICROCOMPUTING #73 Jan 1983 (v.7#1) pg. 56

Detecting sound. Design and construction of electronic circuits that respond to the presence or absence of sound. Circuits include a sound-activated relay, sound-level meter, and an adjustable-frequency tone source.
MODERN ELECTRONICS [2] Oct 1985 (v.2#4) pg. 58
Added Info MODERN ELECTRONICS [2] Jan 1986 (v.3#1) pg. 5

Sound-level meter incorporates a visual LED bar graph readout with a range of 30 to 120 dB. Est. cost: $48 (kit).
POPTRONIX HOBBYISTS HANDBOOK Winter 1996 pg. 55

"Riot Restrainer". Alarm sounds when noise exceeds a predetermined level, turns off when noise level goes down.
POPULAR ELECTRONICS [1] Apr 1969 (v.30#4) pg. 47

Listen to a new world of sounds with an ultrasonic detector. This inexpensive detector converts ultrasonic sounds from insects, compressed gas leaks, small animals, etc. into an audio output.
POPULAR ELECTRONICS [1] Jul 1978 (v.14#1) pg. 64

Electronic "knock detector" helps trace down the source of strange knocking noises in electro-mechanical devices, such as automobile engines.
POPULAR ELECTRONICS [2] Aug 1989 (v.6#8) pg. 81

Sound-level meter circuit uses LED's to indicate sound levels from 65 dB up to 115 dB or more. Four sensitivity ranges are controlled by a rotary switch.
POPULAR ELECTRONICS [2] Oct 1989 (v.6#10) pg. 84

Fun with op-amps. Part 2. (1) Operation and theory. (2) Telephone amplifier circuit for hearing impaired or noisy environment. (3) Audio alarm sounds a buzzer when the noise level gets too high.
POPULAR ELECTRONICS [2] Feb 1992 (v.9#2) pg. 68

Build a sound-level meter with a dynamic range of 30 to 120 dB. Est. cost: $48 (kit).
POPULAR ELECTRONICS [2] Nov 1995 (v.12#11) pg. 56

Patio alert. A wireless receiver which can be activated by three transmitters which in turn can be activated by anything that makes a noise (doorbell, telephone, baby crying, etc...). House wiring carries signal. Receiver buzzes and turns on a light indicating source of noise.
POPULAR SCIENCE Apr 1972 (v.200#4) pg. 115

Circuit monitors sound level and lets you know when it rises above or falls below a predetermined level.
RADIO-ELECTRONICS Jan 1980 (v.51#1) pg. 68

A circuit which will generate a direct-current voltage whenever a radio loudspeaker is activated. Use the circuit as a form of "sound" detector to control some other device.
RADIO-ELECTRONICS Jul 1983 (v.54#7) pg. 77

Detecting signals with noise. Exploring the phenomenon called "stochasic resonance" where electronic noise can boost an otherwise weak signal above the threshold of detection. Requires the construction of a threshold detector circuit, noise module circuit, and signal module circuit. Est. cost: $100.
SCIENTIFIC AMERICAN Aug 1995 (v.273#2) pg. 100

Sound level meter incorporates the Panasonic omnidirectional electret condenser microphone.
SPEAKER BUILDER 1/1986 [Apr 1986] (v.7#1) pg. 34
Correction SPEAKER BUILDER 2/1986 [May 1986] (v.7#2) pg. 44

Converting Radio Shack's sound level meter to also function as a millivolt (mV) testmeter to measure loudspeaker response.
SPEAKER BUILDER 4/1994 [May 1994] (v.15#4) pg. 12
Correction SPEAKER BUILDER 6/1994 [Aug 1994] (v.15#6) pg. 53
Correction SPEAKER BUILDER 5/1995 [Jul 1995] (v.16#5) pg. 68

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