On Fri, 20 Apr 2001, Phil Mendelsohn wrote: > On Fri, 20 Apr 2001, Bill Layer wrote: > > > That 'circuit' will be a patch cord from the audio jack, running through a > > resistive divider or L-pad (passive control, like a pot) right to the > > meter's input. This is the beauty of it, we don't need to engineer any > > digital hardware... all in the analog domain. Childs play. > > Far be it from me to mess with your fun, but you're making this way too > hard. You don't need the sound card. Any signal where it's integral can > be proportional by some factor to the amount of RAM will do. You only > need a couple of caps, a couple of resistors, and probably a $.25 buffer > amp. Take a signal from the PC speaker line, or a serial line. Or use > the sound card. Really, I think you can do this for about a dollars worth > of parts, besides the meters. Wait, skip the buffer amp. Just use a single transistor as a voltage follower. You now need a couple more resistors, maybe a couple more caps. To do the log scaling from a soundcard out, you're going to rectify it back to DC, then need a log amp (or SSM / Analog Devices / THAT audio integrated level driver). Why not stay DC and keep it simple? And keep your sound card for tunes? -- "To misattribute a quote is unforgivable." --Anonymous