I wouldn't be the least bit surprised if the sound wasn't coming from a disc ceramic capacitor. They are good at being somewhat piezoelectric. I have seen them generate audio in an amplifier where I was using them in the input stages. A tap with a finger sounds like somebody playing with a microphone. Once, I put a .05uf 50-volt disc capacitor across the output of a signal generator and fed about three or four volts in to it. You could clearly hear the whine when the signal generator was anywhere above about 1khz or so. It is probably pretty hard to localize the sound in a small board, but the disk capacitors are a good place to start. It may be necessary to use some other type of capacitor to cure the problem as a replacement ceramic disk will probably do exactly the same thing. Martin McCormick WB5AGZ Stillwater, OK 36.7N97.4W OSU Center for Computing and Information Services Data Communications Group In message , Moritz von Buttlar writes: >> Can anyone tell me why my 16c84 is making a buzzing noise. I am a novice >> and this is my first project. It is a very simple gate controller that >> checks 6 inputs to see if the gates are closed. If a gate is open it takes >> that bit high to switch a led on. >> >> The controller works well but makes an irrataing buzzing/whinning noise. >> Any ideas?? >> >> Thanks in advance. >> >> Andy Parry >> Durban >> South Africa.. > > >Hi ! > >Do you use an RC circuit for the oscillator ? Maybe the sound is derived >from a really low oscillator frequency. Check out if this part of the >circuit works properly, try changing the values of the components (or put >a variable resistor in series with the other resistor) and hear if the >sound changes also its frequency. > > Just an idea, > > Moritz > > >-------------- >Moritz von Buttlar "...und denkt daran...Viel Wurstwasser trinken ! >Kiel, Northern Germamny Das schaerft den Verstand !" >+49-431-542834 Werner >## CrossPoint v3.02 ##