From: "Bob Blick" > Kyrre Aalerud said: > > Problem is transferring to PC takes time, so unless I did this in USB2.0 > > I'd have to capture, then send all data and wait for trigger again. > Are you also considering what it takes to display this data realtime? Are > you an experienced DirectX programmer? > Otherwise you'll be stuck with a fancy "datalogger". I will be using LabView to receive and display/log/zoom the data. As long as one has some power in the computer this won't be any problem. The data transfer on the other hand will take sooooooo much longer than the capture anyway, so realtime is out of the question. I may add USB2.0 later but for now I'll use paralell (i think). > Input preamps are another thing you need to be pretty experienced at in > order to build something decent. I know. I will do it very simple. I will use i2c controllable resistors, (Yes they exist!), to let PC adjust input amplification/dampening. The final amp will be responsible for clipping the input so that teh ADC won't go bonkers on me. (It only withstands minor errors like -0.1 volt below gnd and +1 or 2 volts above vcc.) I will be using amps that are spec'ed far beyond 80 MHz in order to not disturb the signal too much... However, I don't mind a little harmonic distortion and other wierdness as this will be a oscilloscope to debug digital circuitry. That way, as long as I have a accurate clock I will be able to see or verify timing-issues and sneak-a-peak at other data-traffic. I will also get a good indication of the signal-levels. No need to have them within the microvolt. > I realize I sound like a wet blanket, but there's a reason why > oscilloscopes are priced the way they are. It costs money to make a good > one. Not at all. Theese are important issues. As long as I know what I need I think I'll be fine. I do have some experience with mixed logic layout. Both in PCB size and in integrated design. -- PCB is a cinch compared to integrated though :-) > At the very least, you should buy a used analog oscilloscope and use the > frontend and trigger sections. Then you only have the digital and software > challenges. > Cheerful regards, > Bob Every adjustment will be in software... Fancy looking! The scope hardware will be a black box with a good connector :-) KreAture -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.