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December 31, 2012 AT 3:00 pm

Automatic Volume Control using IR LED

TVBTamed

Here’s a great project from “Paulc1″ in the Adafruit Forums — instead of a TV-B-Gone, it is something of a “TV-B-Tamed.” I really need one of these for my Raspbmc with its streams of web audio with highly compressed commercials as well as TV streams. ;)

Read more over at the forums to see the problem solving steps the maker went through to tune for specific televisions that weren’t responding.

Out of frustration over TV stations and advertisers’s intrusive actions raising volume during commercials, and inspired by Adafruit’s tutorial on IR Detectors, I built a mouse trap with a Mic and an IR sending LED that could be set to a HI/LO level beyond which the gadget would send an IR code to either lower or higher volume if those limits were exceeded.

It consists of a mic feeding an amplifier with adjustable gain and sensitivity ,with the output to an analog input of an Atmega328 programmed to send a pre-set HI/LO IR codes if exceeded.to an IR LED.

A 4Quad comparator compares the signal level with a voltage divider of 4 resistors adjusted to a logarithmic Db levels,and the output to 4 led’s as volume bar.

The Two pots are for gain control and LCD backlight. A regulated 7805 power supply and indicator light are shown at the bottom right and a 6pin ISP was wired at top right to be able to reprogram the chip. A pin 13 red led by the IR LED shows IR activity.

Read more.

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