Somehow I wound up replying directly on this, so here it is again... (Sorry Lawrence) The bitscope project is nice. Velleman has some assembled PC scopes at about the same price point (with plusses and minuses over bitscope). I've been spoiled to have Tek and HP analog and storage scopes over my entire career, but I've often thought that for the hobbyist, a scope is a big investment. The PC soundcards scopes are probably better than nothing but not accurate for quantitative measurements. I've often wondered what you could do to make a cheap hobby scope. I've thought about an A/D, a counter, a memory system, and a CPU, but then you have bitscope and you probably can't do it for much less money. $200-$300 will buy a pretty nice used scope so there isn't as much incentive. Some of my wilder ideas: It sure seems like you could make a multisync monitor into a bizzare scope with just a little hassle. 15" monitors are cheap as can be these days. Drive the horizontal at the sweep frequency. You can convert the signal to 8 bits using an A/D and feed the green (mono) input. Count lines to skip a little bit between "traces" and use a counter to generate a vertical sync. So you wind up with a 3D scope where the amplitude is the brightness of the "trace" and you get a bunch of traces on the screen at once. Probably not very practical. We've all see the propeller clocks and the little LED "metronomes" that display messages in the air. Wouldn't a scope like that be cool? An LM3909 (bar graph driver, right?), and LED bar, and a motor spinning at the horizontal sweep frequency. Blank it between pi and 2pi. I wonder if you could have one blade of the propeller do channel 1 and the other blade channel 2? While one is blank, you drive the other one (chop only, no alt). I remember seeing plans years ago for driving an old TV's sweep circuits to make a scope. That's always been an interesting idea to me but it seems too hard to go find the right spots. Easier to display on a PC. A while back I did a "stamp project of the month" where we took our APP-II (basically a PIC16F873) converted analog samples and drove a VB program to make a kind of scope. Not especially fast but sort of cool. Anyway, just random musings.... Al Williams AWC * Floating point A/D http://www.al-williams.com/awce/pak9.htm > -----Original Message----- > From: pic microcontroller discussion list > [mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of Lawrence Lile > Sent: Wednesday, February 06, 2002 1:51 PM > To: PICLIST@MITVMA.MIT.EDU > Subject: Re: [EE]:Oscilloscope > > > I knew somebody had done it. > > BTW, the link you sent was really interesting, but didn't seem to have > much to do with a scope. --Lawrence > > ----- Original Message ----- > From: "Dal Wheeler" > To: "Lawrence Lile" > Sent: Wednesday, February 06, 2002 12:42 PM > Subject: Re: [EE]:Oscilloscope > > > > Doesn't this sound like the Bitoscope project? > > > > I thought about rolling my own someday too though... > Something roughly > > like this: (only faster) > http://www.techmind.org/vd/mk1/vdescrpt.html > > Slap a different trigger on it; higher clock and smaller > buffer, multiple > > similtaneous channels, 8 fast comparitors into an extra > FIFO,No fpga on > > it...? > > > > :') > > > > > > ----- Original Message ----- > > From: Lawrence Lile > > To: > > Sent: Wednesday, February 06, 2002 10:37 AM > > Subject: Re: [EE]:Oscilloscope > > > > > > > Maybe un-useful, but one I have thought of often. Here's my > > > thinking: Forget trying to get high speed analog signals > into your > > > PC. Have an external box that captures the waveform, scales it, > > > isolates it from > your > > > precious PC's ground and power supply, and also scales it in the > > > time dinemsion, and wraps a nice ground plane around it.. Jam a > > > bitstream > into > > > whatever port is easy - RS232, parrallel, or USB (if it were a > commercial > > > product USB would be the way to go) and use the PC's megabytes of > > > memory > > for > > > the digital storage, use the PC's powqerful graphics for the > > > display, > and > > > use the brain for things like displaying the RMS value as > a digital > > > voltmeter, counting the frequency, counting the pulse > width, all the > > things > > > that take a lot of squinting or guessing on an old analog > scope. At > least > > 4 > > > channels, plus a few logic channels like an HP mixed signal scope. > > > > > > Now if we are going to measure signals in the megahertz range, we > > > are > out > > of > > > the PIC's league. How do TEK and the other big boys achieve A/D > > conversion > > > in a 100 mHz scope? > > > > > > keep in mind this is just an interesting mental excercise > - I'm not > > planning > > > on building this anytime soon. Besides, they already make them. > > > > > > --Lawrence > > > > > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > -- 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