nolram Posted October 25, 2005 Report Share Posted October 25, 2005 Good day! I am having a hard time computing the gain of the resistor-switch network of a digital volume control published in electronics-lab.com. The author is unknown. Can anyone shed light on this? Quote Link to comment Share on other sites More sharing options...
Guest Alun Posted October 25, 2005 Report Share Posted October 25, 2005 Plkease provide more information, like a link to the area of our site, finally it's highly unlikely that anyone will email you with your request. Quote Link to comment Share on other sites More sharing options...
audioguru Posted October 25, 2005 Report Share Posted October 25, 2005 Hi Nolram,Welcome to our forum. ;DWe have two Digital Volume Control projects. Which one are you talking about?http://www.electronics-lab.com/projects/audio/010/index.htmlhttp://www.electronics-lab.com/projects/audio/033/index.htmlThe 1st one doesn't have a debounce circuit for the pushbuttons so the volume would switch thru many steps each time a button was pushed. It also seems to have the resistors in the wrong places. The volume steps are affected very much by the input impedance of what it drives. The 2nd needs the audio to be DC-biased which isn't shown. It has linear steps which are crammed together and hardly noticed near max volume and huge steps in volume near minimum volume. In the middle of its 64 steps the volume is reduced only a little.Maxim and I think Texas Instruments make modern volume control ICs that don't have the problems of these projects. Some of them are stereo. Quote Link to comment Share on other sites More sharing options...
nolram Posted October 31, 2005 Author Report Share Posted October 31, 2005 Good day! Ok. The one that employs cd4066. God bless! ;D Quote Link to comment Share on other sites More sharing options...
Staigen Posted October 31, 2005 Report Share Posted October 31, 2005 Hey Audioguru, take a look at the first one you linked to, what is the 555 doing there? Also look at the resistor divider, isnt that one backwards? And, why 74193? A 40193 is the same, and cmos! There are many moore errors there!/Staigen Quote Link to comment Share on other sites More sharing options...
audioguru Posted October 31, 2005 Report Share Posted October 31, 2005 Hi Staigen,People who post fuzzy Jpeg schematics should be shot! >:(1) The output of the 555 is missing a wire at the left side of the schematic connecting it to the "up and down" buttons.2) Yes, the ladder is backwards.3) Maybe the author had a spare 74193 and wanted to heat his home with its massive power requirement. Sure a Cmos one would be fine but probably wasn't invented then.I didn't look at the fuzzy pic anymore because it was making me blind. It seems to be a very old circuit, since digital pots ICs are common today, even stereo ones with memories. ;D Quote Link to comment Share on other sites More sharing options...
nolram Posted November 3, 2005 Author Report Share Posted November 3, 2005 can anyone provide me with a schematic diagram of an automatic gain control circuit. thanks... ;D Quote Link to comment Share on other sites More sharing options...
audioguru Posted November 3, 2005 Report Share Posted November 3, 2005 Hi Nolram,I'm glad you abandoned the obsolete project that is wired wrong.A very good Fast Audio Peak Limiter project is here: http://www.sound.westhost.com/project67.htm Quote Link to comment Share on other sites More sharing options...
V8meathead Posted November 4, 2005 Report Share Posted November 4, 2005 haha audioguru your second to last post cracked me up! Quote Link to comment Share on other sites More sharing options...
nolram Posted November 4, 2005 Author Report Share Posted November 4, 2005 thank you audioguru, u r such a great help. ;D Quote Link to comment Share on other sites More sharing options...
nolram Posted November 4, 2005 Author Report Share Posted November 4, 2005 thanks for all of you guys who posted ur opinions concerning my problem. Can i ask another favor? Please provide me some links to pages where i can get mcu-based automatic gain control. This will be a very great help on my project. Thanks. God bless. Quote Link to comment Share on other sites More sharing options...
audioguru Posted November 4, 2005 Report Share Posted November 4, 2005 Maxim and TI make volume control ICs that use MCU control. Then you'll need to make your own A to D converter for the MCU to sense the levels. Quote Link to comment Share on other sites More sharing options...
nolram Posted November 4, 2005 Author Report Share Posted November 4, 2005 ok audioguru. thanks a lot. :D Quote Link to comment Share on other sites More sharing options...
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