big VU meter

1-32 — elektor january 1981 the big VU meter ... Many designsfor digital (LED) VU meters have found their way into the pages of Elektor in the past. This type of meter is normally used to monitor the amplitude of audio signals by means of a row LEDs. The level indication is provided either by a single LED being lit, or by a "bar" of LEDs — the more sophisticated versions allow a choice between the two. The VU meter presented here can be considered as having two completely separate sections, namely a low voltage section and a high voltage (240 V) sec- tion. The circuit diagram of the low voltage section is given in figure 1. As can be seen, the input signal is fed to the sensitivity control potentiometer, P1, via resistor R 1 . When this potentio- meter is adjusted to give a voltage of approximately 1 Veff on its wiper the display will give a maximum indication of +6 dB. A wiper voltage of around 0.5 Veff will then give a reading of 0 dB. Input overload protection is provided b...