If you want the dynamics of the music signals to visual representations of 20-segment LED indicator bargraf covering a dynamic range of 60dB, you are the right place.
Designed as an attractive desktop VU meter for home audio, has its own power supply, linear frequency range and excitement of the speaker directly.
Simplicity, low number of components, small size and adaptability to different amplifiers with different power and speaker impedance makes the device to be desirable and attractive visual indicator of each Hi-Fi enthusiast.
Most audio sources (radios, CD players, tape …) during the playback of your scores do not exceed dynamic range (dynamic range) the sound of 60dB.
These data determine the number of required LED indication light diodes for power to be measured.
Mon rational reading of 3dB of each individual LED diode and the target range of 60dB to specify the exact number, VU meters with 20 LED diodes.
Recall the front page of emitter no. 7-8 since 1996. command when it was released documentary of my electronics lab, where the right corner of the board, in part for AUDIO TEST, seen embedded VU meter with ten LED diodes. Prilozham nostalgic wanted to link to that number, but the website of my favorite magazine is still under construction (not included numbers from 1996) and therefore attach alternative link where you can view the built-in VU meter with 10 LED diodes.
I do not know if you remember the time when there was no integrated circuits, so painstakingly tried to make VU meter with a series of transistors, one for each LED diode indication, one transistor as a source of constant current and voltage divider. Imagine now had to prepare the AKP over 20 transistors, 60 resistors and 20 diodes LED. Fortunately, we now have integrated circuits. LM3915 is a “drug of choice.”
Author: Primarius D-r Petar Avramovski, writer to magazine Emiter.
The complete article you can read the pages of the Emiter 9/2011.