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Room Noise Detector

This circuit is intended to signal through a flashing LED, the exceeding of a fixed threshold in room noise, chosen from three fixed levels, namely 50, 70 & 85 dB. Two Op-amps provide the necessary circuit gain for sounds picked-up by a miniature electret microphone to drive a LED. With SW1 in the first position the circuit is off. Second, third and fourth positions power the circuit and set the input sensitivity threshold to 85, 70 & 50 dB respectively.... [read more]

Power amplifier 2X5W with TDA1516Q

A simple STEREO amplifier, with minimal external components. It use one only opamp., that is capable to give output power 2X5W in the 4 ohms, with distortion 0.5%.... [read more]

Dual-rail Variable DC Power Supply

This simple unit provides a dual-rail variable output ranging from ±2.5V to ±15Vdc with precise tracking of the positive and negative output voltages, still retaining the current limiting and short-proof capabilities of the "master" circuit. As the purpose of such a dual-rail design is to supply experimental or under-repair circuits, the maximum current output delivered was deliberately kept to about 500 - 600mA per rail, thus avoiding the use of expensive power transistors and complex circuitry.... [read more]

Relay Timer switch

Relay Timer switch... [read more]

Headphone Amplifier

Headphone Amplifier... [read more]

25 Watt Audio Amplifier Circuit

This is a 25 Watt basic power amp that was designed to be (relatively) easy to build at a reasonable cost. It has better performance than the standard STK module amps that are used in practically every mass market stereo receiver manufactured today.... [read more]