audio traffic light - visual level monitor for preamplifiers

audio traffic light elektor march 1983 What has a traffic light got to do with audio? Nothing, really, but this particular circuit drives three LEDs; the colours are red, orange (amber!) and green, and they are mounted in a vertical line in this order. When we saw the prototype, it reminded us of ... Yes. Well. This circuit does have a rather different function. The LEDs indicate the level of the output signal from a preamplifier, allowing one to judge the quality and quantity of the signal being fed to the power amplifier. This makes the circuit a useful accessory for the Prelude preamplifier in the XL range, as well as for other preamplifiers. audio traffic light visual level monitor for preamplifiers For the level indication on the Prelude preamplifier, we decided to depart from the usual VU meters and LED bar indicators. These accessories on a preamplifier usually provide little in the way of information and merely swing nicely in rhythm with the music — althoug there are of...