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PC oscilloscope

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wutang

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hi guys!
i want to build a digital oscilloscope for for a school project
i seen this pc oscilloscope on the internet abd by its functions it is way cool
does anyone have an idea on how to build one?
coz i have this crazy idea of buying it but i dont want to spoil the thrill of building my own... hehehehe
 
sure , get an A/D converter , store the data in PC memory or on disk .
that is the jist of it..
Analog Devices make some "nice" converters..
if you have a PC with a spare ISA bus slot i have a schematic for the data collection part , which will get the data from the analog to digital converter , and store it in memory..
it helps to know a pc language like pascal to do the data collection routine..
 
I have a bitscope, and from the schematics and info that i've looked at for it, there really is no "magic" going on... it really is as simple as sampling an A/D, storing it in a buffer, and then sending it to the PC periodically. However, obviously the challenge comes in when you look at the operation frequency... the bitscopes are sampling somewhere in the range of up to 40 million samples per second (if not more), so you have to use an A/D, controller (presumably an FPGA or something), and memory that can handle that kind of speed.

My major complaint with the bitscope (besides the software, but that's a whole different story) is that they only used an 8-bit A/D converter.

so if you're going to try to build your own, you should try to use an A/D with more bits :lol:
 
evandude said:
My major complaint with the bitscope (besides the software, but that's a whole different story) is that they only used an 8-bit A/D converter.

so if you're going to try to build your own, you should try to use an A/D with more bits :lol:

The obvious reason for eight bit is speed! - the more bits you use the slower it will all run (including the data transfer), eight bits gives you over 0.5% resolution, which is probably more than enough? - unless you are wanting to vertically expand a small section of waveform?.
 
Yeah, I know 8-bit is for speed, but actually staring at the waveform, it really doesn't look very good! pretty much any point where it holds a relatively steady voltage is just a "fuzz" of it flipping a bit back and forth... this waveform looks like a pretty clean digital waveform on a normal bench-top digital scope, and looks like only a fuzzy, sketchy rendition of it on the bitscope... and that is a very low-speed signal!
 
evandude said:
Yeah, I know 8-bit is for speed, but actually staring at the waveform, it really doesn't look very good! pretty much any point where it holds a relatively steady voltage is just a "fuzz" of it flipping a bit back and forth

More bits would probably make that worse! - I don't see as that's related at all to being only 8 bit? - it looks to be a noise problem?. The changes look to be much more than one bit - unless you've got it expanded greatly? - in which case your effective resolution is far less than 8 bits.
 
So as you can see you have to make a decision right off ..
Eight or twelve bits.. I would go with eight to start with , and later on when you have everything worked out ,maybe try twelve..
You also have to choose which A/D converter to use ..
 
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