Audio Amplifier Projects

passive VU meter
If you want to fit your loudspeaker enclosure(s) with a drive indicator, it is best touse a unit that does not need a powersupply. This article describes a passive VUunit for smaller amplifiers and loudnesses—see Fig. 1. It consists of a rectifier and six(may be fewer or more) identical stagesthat each comprises a […]

AF input selection
Use is made of a single-pole, 12position rotary switch, S1, with whichand 12 pull-down resistors the inputsource is selected. Since only one resistoris linked to the positive supply lineat any one time, the current drawn bythe circuit is only 15 μA, which, in thecase of a battery operated preamplifier,is an important advantage.

digital VU meter - 2
After last part detailed description of thedesign and facilities ofthe accurate, multifaceted digital vu meter,this part’s final instalment deals with the construction and operation of the instrument.