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Save Your Ears - A Noise Meter Circuit

‘Hello… HELLO! Are you deaf? Do you have disco ears?’ If people ask you this and you’re still well below 80 , you may be suffering from hearing loss, which can come from (prolonged) listening to very loud music. You won’t notice how bad it is until it’s too late, and after that you won’t be able to hear your favorite music the way it really is – so an expensive sound system is no longer a sound investment. To avoid all this, use the i-trixx sound meter to save your ears (and your neighbor's ears!).... [read more]

Self-powered Sine to Square wave Converter

This circuit is intended to provide good square waves converting a sine wave picked-up from an existing generator. Its major feature consists in the fact that no power-source is needed: thus it can be simply connected between a sine wave generator and the device under test.... [read more]

Vehicle Anti-Hijack Alarm No3

Like the first two Hijack Alarms - if a door is opened while the ignition is switched on - the circuit will trip. And after a few minutes delay - when the thief is at a safe distance - the Siren will sound. But this time the engine does not go on to fail automatically. Instead - it will continue to run until the thief turns off the ignition. Then the engine will not re-start.... [read more]

Transmitter FM 45W with valve

TECHNICAL CHARACTERISTICS: Tendency of catering: 220V AC Frequency of emission at FM: 88~108MHz Force of expense: max 45W (without the R3),... [read more]

IR Music Transmitter and Reciever

Using this circuit, audio musical notes can be generated and heard up to a distance of 10 metres. The circuit can be divided into two parts: IR music transmitter and receiver. The IR music transmitter works off a 9V battery, while the IR music receiver works off regulated 9V to 12V. First diagram shows the circuit of the IR music transmitter. It uses popular melody generator IC UM66 (IC1) that can continuously generate musical tones.... [read more]

Power Amplifier 8W

Although the TDA2030 can deliver 20 watts of output power, I deliberately reduced the output power to about 8 watts to supply 10 watt speakers. Input sensitivity is 200mV. Higher input levels naturally will give greater output, but no distortion should be heard.... [read more]