Electronic Canary

This is a circuit which is a modification of Hartley oscillator with the addition of several components. This circuit uses a small audio transformer, type LT700. The primary of this transformer is center tapped with an impedance of 1Kohms at 1KHz and the secondary has an impedance of 8 ohms. “Chirp” characteristic of this oscillator is given by the inclusion of […]

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Phono Pre-Amplifier

This circuit is a simple circuit that can be used to listening old vinyl discs from a well preserved collection. This circuit efficient for cheap moving-magnet cartridges. It can be used in connection with the audio power amplifiers shown in these article. It also has good RIAA frequency response curve,  good high frequency transients behavior due to passive equalization in […]

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Broadband Noise Generator

To test some electronic systems such as RF communication, filter, or audio we often need random noise source. This article shows the circuit that generates an RMS amplitude regulated noise source with selectable bandwidth. This circuit is suitable for wide range of application since it has 1 KHz to 5 MHz decade ranges selectable   bandwidth and 300mV RMS output. Here […]

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