60-dB LED VU Meter
Published in issue 312, July 2002
Most of the analogue audio media, including radio broadcasting, stick within 60 dB dynamic boundaries. This VU Meter was designed to be used as a desktop instrument with home audio appliances, so it has its own power supply. Driven by an AC musical signal taken directly from low impedance loudspeaker connectors, i.e. in parallel with loudspeakers, and having linear frequency response, it covers 60 dB dynamic range in 3 dB steps using 20 LEDs in a bargraph. Low component count and simplicity enable the circuit to be housed in a small box or behind a transparent shield like a small acrylic desktop photo holder.
Resistors:
R1 = 2kOhm 7 (see text)
R2 = 10kOhm
R3 = 680Ohm
R4 = 22kOhm
R5 = 820Ohm
R6 = 2kOhm 2
R7 = 22Ohm
P1 = 100Ohm
Capacitors:
C1 = 1µ F 63V (MKS, MKC)
C2,C6 = 10µ F 16V radial
C4 = 2nF2 (see text)
C3,C7,C9 = 100nF
C5 = 22nF
Semiconductors:
IC1, IC2 = LM3915N
IC3 = LM7805
D1-D20 = LED
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Click below to download a PDF copy of this article from Elektor magazine. Please note. In view of the complexity of international markets, Elektor cannot guarantee the availability of components for this project.
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