Tag Archives: portable

4 Channel Portable Audio Mixer

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High-quality modular design, 9V Battery powered – Very low current drawing The target of this project was the design of a small portable mixer supplied by a 9V PP3 battery, keeping high quality performance. The mixer is formed assembling three main modules that can be varied in number and/or disposition… Read more »

LEDs Indicate Sound Level

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This Design Idea describes a battery-operated, portable sound level 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.Resistor R1 biases the condenser microphone. C1 couples R1 to transistor Q1. Q1 and R2… Read more »

Hearing Aid

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Portable and easy to built, Uses 1×3v battery Commercially available hearing aids are quite costly. Here is an inexpensive hearing aid circuit that uses just four transistors and a few passive components. Circuit diagram: Hearing Aid Circuit Diagram Parts R1 = 2.2K R2 = 680K R3 = 3.3k R4 =… Read more »