Your best bet would be the MAX038 sine wave generator chip. It has a bandwidth of 0.1Hz to 20MHz. Its frequency can be changed by changing a voltage. You can easily interface a DAC to digitally control the frequency. Go to www.maxim.com and check out the spec sheet. Ben -----Original Message----- From: Allen Mahurin [mailto:wild_wire@YAHOO.COM] Sent: Tuesday, September 25, 2001 7:05 AM To: PICLIST@MITVMA.MIT.EDU Subject: Re: Has this been done before? Speaker testing I'm no PIC expert (yet), but wanted to point out that the "audio" range is typically specified as 20 Hz to 20 kHz. No need to generate quite as low a frequency as you mentioned (I know, not much difference, but it could save you some time/programming). I've done my share of speaker testing on Audio Precision and LMS. It could be interesting to see how a PIC-based measurement system turns-out. :) Good luck, ATM --- Kasm Consulting And Electronic Repairs wrote: > Hello All, > > I have a project that I want to do in a pic but > want to make sure it hasn't been done before. > I really hate re-inventing the wheel. > > Anyway, > > What the circuit will do is have a speaker connected > in a test setup and pass a range of frequencies to > the > speaker testing the impedance at each frequency. I > would > like to have the pic connected to a computer running > a basic program for graphing the results. The > results will > later be used to calculate the enclosure size for > the speaker. > > Questions > > I know I can use a pic with an A/D for measuring a > voltage > but how would you have a pic generate a frequency? > > The frequencies needed are in the audio range from > 1hz to about > 20khz. > > If it hasn't been done already I have a schematic of > the manual > test setup using a freq generator and dvm to do the > test manually. > I could scan and send the schematic if anyone is > interested. > > > > Any help would be great, > Steve > mailto://kcer@home.com > > -- > http://www.piclist.com hint: PICList Posts must > start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other > [BUY]:,[AD]: ->Ads > > __________________________________________________ Do You Yahoo!? Get email alerts & NEW webcam video instant messaging with Yahoo! Messenger. http://im.yahoo.com -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics