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Quad Power Supply For Hybrid Amplifier

This power supply was designed for use with the ‘Simple hybrid amp’ published elsewhere in this issue. It is of course suitable for use in other applications as well. We’ve used a cascade generator for the 170 V, a switch mode supply for the 16 V, a series regulator for the 12 V and a separate transformer for the 6.3 V filament supply. We’ve chosen an LT1074CT (IC1) for the regulator, which means that the circuit can be built with relatively standard components and will have a high efficiency. The power loss is less with this device compared to a linear voltage regulator.... [read more]

Tube power amplifier 5W with EL84

Tube power amplifier 5W with EL84... [read more]

Continuity Tester Circuit Diagram

Having good contacts is important – not only in your daily life, but also in electronics. In contrast to social contacts, the reliability of electrical contacts can be checked quickly and easily. Various types of continuity testers are commercially available for this purpose. Most multimeters also have a continuity test function for electrical connections. A simple beep helps you tell good contacts from bad ones.... [read more]

Portable 9v Headphone Amplifier

The main requirement was to power the circuit by means of a common, PP3 (transistor radio) alkaline battery. So, implementing a low current drawing circuit was absolutely necessary, though preserving a High Quality performance.... [read more]

A Low Power Wireless Audio Power Amplifier

Using this low-cost project one can reproduce audio from TV without disturbing others. It does not use any wire connection between TV and Loud Speaker. In place of a pair of wires, it uses invisible infra-red light to transmit audio signals from TV to Loud speakers, Without using any lens a range of up to 6 meters is possible. Range can be extended by using lenses and reflectors with IR sensors comprising transmitters and receivers.... [read more]

Analog Milliamp Meter Used as Voltmeter

A milliamp meter can be used as a volt meter by adding a series resistance. The resistance needed is the full scale voltage reading divided by the full scale current of the meter movement. So, if you have a 1 milliamp meter and you want to read 0-10 volts you will need a total resistance of 10/.001 = 10K ohms.... [read more]