Hi - I'd really like to get a scope and a logic analyzer. I'm a poor college student in debt to his knees, so I really don't want to buy them... So - I'd like to try to make them. I found this: http://www.xs4all.nl/~jwasys/old/diy2.html - 8 channel logic analyzer at up to 1Mhz. Prettty sweet, eh? Has anybody seen anything better? What about any DIY scopes? I remember a while back somebody posted some screencaps of a scope he was making with a PIC. Anything like that around? I've also heard of scopes using gameports (joystick ports) - but being that my lappy doesn't have one of those, that isn't of much interest to me.
I used this to calibrate my sound generator. It is limited to the souncard's ADC and at the mercy of your input signal condition but it is free. There is this schematic as well but building it from scratch would most likely cost more than purchasing one second-hand.
I was working on a home made signal generator which would in theory allow me to generate waveforms to what I think was around 90MHz, but getting a real job (tm) put pay to that little project (The idea being if I could take it into university to calibrate it against a scope, and then have something I can test a home made scope against). For a 500KHz USB scope project this might be worth a look:http://www.eix.co.uk/Ethernet/USB/Welcome.htm
here's a link for an Australian company that sells a range of projects to run from a PC. http://www.ar.com.au/~softmark/index.html the oscilloscope is here http://www.ar.com.au/~softmark/page30.html not exactly the cheapest option, but compared to a full sized CRO it's very cheap.
What sort of sample rate and accuracy are you looking for? I'm in the process of trying to make a 4 channel scope based on 4 pics and a PCs parallel port. Each PIC will take samples at 25kHz, but the time at which samples are taken are offset so 2 or all 4 inputs could be tied together to sample at 50 or 100 kHz. Accuracy probably wont be very good because I've run out of pins on the PICs, so am having to use the power supply as reference. Total price so far £4 for the 4 PICs (actually got 5 for £4, but I burned one doh) + £2 for the clock. I haven't tried taking any samples at high speed yet though so I don't know how well it's going to work out.
Take a look at the back issues of "Everyday Practical Electronics" Magazine (EPE). A couple of years ago, they did a PIC 16F877 based dual channel oscilloscope that worked through the parallel port of the PC, like you're trying to make. It was rather low frequency, (only accurate to about 10kHz, though it did continue to work reasonably well above this point, up to about 25kHz like the design being made by davew) I suspect that you could use the design as the base for a better version using USB and a faster PIC for higher frequency use with a bit of effort. It could also do FFT, and the software for the PC side is still on their website, as is the PIC ASM code, and a link to download the software for the PC side of it. Finally, they will even sell you the PCB, so all you need to do is buy the components and solder it together. As you're in the US, I've posted the US version of the relevant website page below. Hope it helps http://www.epemag.com/1000p2.html Finally, Oscilloscopes are cheaper than you might think, if you look in the right places. Ebay can be suprisingly cheap sometimes, as can be junk centers; I got a useable secondhand 10MHz dual channel Phillips scope from one for just £20, and it even recently recalibrated.
indeed i got a fluke scope meter 123 SCC (hooks upto computer, 20mhz handheld dual channel, great with me moving around soo much lately, i also can take it onto campus, fluke's have some great tools). for a bargin price (not even 1/4 of the RRP) and got it calabrated for free You can make software ones using the sound card that are better than the EPE version. This really isn't bad, as a modern sound card samples at 192khz @ 24bit resolution. This is between -/+ 1v so you need to use an op-amp to scale.
I'm wondering if a video capture card can be used as an oscilloscope. Since video signals go up to 6MHz, 5MHz can be easily attained and a good card might be able to attain 10MHz or even 15MHz.
if you have an old TV, and enough know how to make a sawtooth wave generator that can source around an amp you can disconnect the aiming coils and use the sawtooth wave on the horizontal coil and the amplified signal on the vertical coil and get yourself a home brew o-scope - the original idea comes from here: http://www.angelfire.com/80s/sixmhz/tvscope.html lots of cool stuff to check out on that site
