Subscribe
 


IR remote stereo volume control



IR remote stereo volume control
Related Videos

Use the remote Volume Up and Volume Down buttons to increase or decrease the volume. When the volume is changed, the gain, display and bar-graph meter are updated appropriately.

My home stereo uses a pair of powered studio monitors, so I don't have an integrated amplifier/tuner. Instead, I have an old NAD Model 1000 stereo preamp, which is really just a fancy switchbox with a phono preamp (all discrete!), tone and volume controls, and a headphone jack. 

One thing it doesn't have is a remote volume control. For a long time, this hadn't been a problem, since all I used the stereo for was listening to music. Now that we've got the TV, the Mac mini (used as the DVD player as well as a DVR with EyeTV) and the cable box hooked up to it, lack of remote volume and mute control has become quite annoying. (We HATE commercials.)

But I'm an engineer ... I can build my own remote volume control! And I did. Here's how.

Digital control of analog audio volume control is easy if you use a TI PGA2310 stereo volume control chip. It uses a simple 16-bit SPI interface to load two eight-bit gain-set words, one for each channel. The gain ranges from +31.5dB to -95.5dB in 256 0.5dB steps. The chip uses 15V rails for its audio amplifiers and +5V for the digital section. (The much-cheaper PGA2311 uses 5V analog rails.) Basically, each channel consists of a stepped attenuator where laser-trimmed resistors set the attenuation, followed by a variable-gain buffer. The buffer is capable of driving 600Ω loads, so an external line driver is not necessary (for single-ended applications).

Authored by Andy at The Punk Engineer, Added: 25 Dec 2006




http://www.latke.net/blog/punkengineer/archive/000049.html

Unsorted Pool