I present to you a simple project indicator audio signal, a distinctive feature of this project from others is that in the scheme for each channel I primel 32 LEDs to get the long line. At the heart device - AVR microcontroller Atmel ATmega8535, ULN2803 - 8-channel key Darlington, moreover, operational amplifiers, his appointment think it's also clear. Sensitivity indicator is adjusted by resistors R32 and R33, for each channel separately. This project is my thesis work I did a couple of years ago, when the scheme came across sharilsya in folders on your PC, and decided to send to the site.
The scheme is quite large, reduce LED designation did not, the scheme can be found below:
The entire device is going on a breadboard, PCB did not draw who liked the project can draw the circuit board and send it to the forum. All radio components in the circuit can be replaced by a similar, resistor and capacitor can be placed close to par. The transistors may be replaced by any other similar. Crystal oscillator can be put on 14-16 MHz, is not critical. Photos of the device below:
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When programming the microcontroller does not need to put fuse bits, ie we select the desired controller in the program, open firmware and click flash. If the device is assembled correctly, the circuit work immediately.
Original article sourse cxem.net