greyelf@wpi.wpi.edu (Michael J Pender) (11/29/89)
Does anyone know of any cheap oscilloscope kits? I have an old tube oscilloscope here by Tektronix, an RM545. Since the instruction manual was printed in 1964 I imagine its out of warranty, and its definitely out of calibration. In addition the sweep is flaky. Are there any companies that sell oscilloscope kits? student discounts?
doug@psuhcx.psu.edu (Doug Hughes) (12/01/89)
In article <5862@wpi.wpi.edu> greyelf@wpi.UUCP (Michael J Pender) writes: >Does anyone know of any cheap oscilloscope kits? I have an >old tube oscilloscope here by Tektronix, an RM545. > >Since the instruction manual was printed in 1964 I imagine its >out of warranty, and its definitely out of calibration. >In addition the sweep is flaky. > >Are there any companies that sell oscilloscope kits? student discounts? I remember that last spring (or so) someone had posted to the net about making an Apple II into an oscilloscope. I don't remember who it was, but at that time he said he was very busy preparing his Thesis, but had the schematics for doing it on his mac or something. I don't even know if he's around anymore. I used to have his address and wrote to him a few times about it. But he was always too busy. He said that it made a fair oscilloscope too. I'd love to get my hands on those plans!! Anybody else out there ( or this person if he's still around) have plans like these available? I'm sure people would love to see them, and even pay. Doug Hughes doug@hcx.psu.edu {mcvax,gatech,rutgers}!psuvax1!psuhcx!doug
gwyn@smoke.BRL.MIL (Doug Gwyn) (12/01/89)
In article <5862@wpi.wpi.edu> greyelf@wpi.UUCP (Michael J Pender) writes: >Are there any companies that sell oscilloscope kits? student discounts? The only one I know of is Heath. The nearest HeathKit store to Woopie Tech used to be in Wellsley Hills when I lived there several years ago.
cbdougla@uokmax.ecn.uoknor.edu (Collin Broadrick Douglas) (12/01/89)
In article <1935@psuhcx.psu.edu> doug@psuhcx.psu.edu (Doug Hughes) writes: >In article <5862@wpi.wpi.edu> greyelf@wpi.UUCP (Michael J Pender) writes: >>Does anyone know of any cheap oscilloscope kits? I have an >>old tube oscilloscope here by Tektronix, an RM545. >> >>Since the instruction manual was printed in 1964 I imagine its >>out of warranty, and its definitely out of calibration. >>In addition the sweep is flaky. >> >>Are there any companies that sell oscilloscope kits? student discounts? > >I remember that last spring (or so) someone had posted to the net about >making an Apple II into an oscilloscope. I don't remember who it was, but >at that time he said he was very busy preparing his Thesis, but had the >schematics for doing it on his mac or something. I don't even know if he's >around anymore. I used to have his address and wrote to him a few times >about it. But he was always too busy. He said that it made a fair oscilloscope >too. I'd love to get my hands on those plans!! Anybody else out there ( >or this person if he's still around) have plans like these available? >I'm sure people would love to see them, and even pay. > Doug Hughes > doug@hcx.psu.edu > {mcvax,gatech,rutgers}!psuvax1!psuhcx!doug > I second this motion. This would be really nice for us poor college student who can't afford to pay $1000+ for an O-Scope. Collin Douglas cbdougla@uokmax.ecn.uoknor.edu
cyliao@eng.umd.edu (Chun-Yao Liao) (12/01/89)
I remembered that I saw such a project in Byte dated back to...1985? or 86. I think it was for Apple computer, but not sure if is for //e or just //+ or maybe it works fine on both. Sorry, don't have magazine with me, can't really tell which issue was that. -- _____________________________________________________________________________ | "When is a revolution legal? When it |Chun Yao Liao +++ cyliao@wam.umd.edu| | succeeds." -August Strindberg | The Oriental from Argentina! | |___________Don't we need a revolution on the computer technology?____________|
brianw@microsoft.UUCP (Brian Willoughby) (12/05/89)
It can be done - but I don't think you can 'purchase' such a beast. You'll
have to design the hardware and software yourself:
I have written a program for my Plus which (with a little hardware support)
gives me much of what I would want an Oscilloscope for, but it is certainly no
replacement. Cost is the governing factor here.
I had already built my own stereo Analog to Digital conversion card, but I had
trouble setting the gain and DC offset controls to get the maximum sound
without distortion. The oscilloscope project grew out of a need for some
graphical feedback during the recording process.
I borrowed a M6840 Programmable Timer Chip from another card I designed, and
used it as a variable time base. The interrupts from the 6840 fetch A/D
conversions from the first card and store them in a buffer, while the main
routine graphs the values to the (single) HiRes screen. The main routine
synchronizes with the interrupt routine so that it does not graph data before
it arrives. The interrupt routines also shut themselves down (i.e. use less
CPU time to allow the graphics routines to run faster) whenever the buffer
has enough data to fill a screen. Then the main routine signals the interrupt
to fill the buffer again as soon as it has finished plotting the current
screen. This technique results in some input data values being lost between
the last data plotted on one screen and the first data plotted on the next
screen. If you are familiar with oscilloscopes, you'll note that they also
cannot display EVERY point, because some time is spent in retrace while the
electron beam is disabled. As an added 'gimmick' feature, I have the main
routine spin until a rising edge is detected. This duplicates the 'trigger'
mode of many 'scopes.
There are also a few other tasks for the interrupt routine - so it doesn't
fully shut down - it just executes fewer lines of code rather than waste
valuable CPU time. I haven't ever seen this technique used in other interrupt
controlled programs, but it really is a time saver. At 1 MHz, the Plus can
handle data reasonably well at the highest A/D rate I need - 48 kHz - but the
screen doesn't update incredibly fast. Slowing the rate to 10 or 20 kHz allows
updates faster than the eye can discern. The problem is that the higher rates
cause the Apple CPU to spend nearly all of its time in the storing of data into
the buffer, and little time is left for graphing. This speed restriction is
removed now that I have an AE TransWarp in my Plus. Even 48 kHz input rates
(in mono) result in very fast screen updates.
Some of the other tasks of the interrupt routine are to keep track of the local
minimum and local maximum for use by a peak indicating bar graph which I
display below the main screen of the 'scope. My purpose for this is so that
any input data above or below the maximum A/D range can be detected even if it
arrives during 'horizontal retrace' or the 'trigger' period.
The average value of each screen of data is computed and displayed (once per
screen, of course) just to the right of the 'scope display. All of these
features together make audio sampling a breeze. Now I just need to redo
everything for the GS (if I ever get one).
P.S. I have the latest sampler from Ensoniq (the guys who made the GS sound
chip [Digital Oscillator Chip]), so I haven't had much use for the old 8 bit
Apple ][ Plus sampler that I designed. Such is the progress of technology.
Brian Willoughby
UUCP: ...!{tikal, sun, uunet, elwood}!microsoft!brianw
InterNet: microsoft!brianw@uunet.UU.NET
or: microsoft!brianw@Sun.COM
Bitnet brianw@microsoft.UUCPgreyelf@wpi.wpi.edu (Michael J Pender) (12/12/89)
In article <1935@psuhcx.psu.edu> doug@psuhcx.psu.edu (Doug Hughes) writes: > >I remember that last spring (or so) someone had posted to the net about >making an Apple II into an oscilloscope. I don't remember who it was, but >at that time he said he was very busy preparing his Thesis, but had the >schematics for doing it on his mac or something. I don't even know if he's >around anymore. I used to have his address and wrote to him a few times >about it. But he was always too busy. He said that it made a fair oscilloscope >too. I'd love to get my hands on those plans!! Anybody else out there ( >or this person if he's still around) have plans like these available? >I'm sure people would love to see them, and even pay. > Doug Hughes > doug@hcx.psu.edu > {mcvax,gatech,rutgers}!psuvax1!psuhcx!doug > I ended up buying a wonderful Hewlett Packard scope from the school here instead, so I'm all set in that department. The reason I'm posting is in response to your request for info on making an apple into an oscilloscope. An apple can easily be made to act like a digital oscilloscope. For a class demonstration one of my professors built one on Friday using an 8085, an 8 bit d to a, and an 8 bit a to d convertor. Most a to d convertors aren't fast enough for high speed signals. If one figures they need about 20 points/cycle with a 100 KHz (fast) a to d convertor the chip could start to lose out above 5 KHz. This is not bad however. Mostly the computer is more useful at lower speeds, where the scope shows a waveform as a slowly moving dot or line, and the apple can instead send the same signal back to the scope at a much higher speed. I'm kind of busy now (middle of finals, I'm about to be a senior), but if there's interest I'll try to find some way to post hardware specs and software for a 6502. --- Michael J Pender Jr Box 1942 c/o W.P.I. ... (Mankind) has already greyelf@wpi.bitnet 100 Institute Rd. used its last chance. greyelf@wpi.wpi.edu Worcester, Ma 01609 - Gen. MacArthur
greyelf@wpi.wpi.edu (Michael J Pender) (12/12/89)
In article <1989Dec1.074746.1759@uokmax.ecn.uoknor.edu> cbdougla@uokmax.UUCP (Collin Broadrick Douglas) writes: [stuff on wouldn't it be nice if someone brought back the oscilloscope conversion plans for an apple} > > I second this motion. This would be really nice for us poor college student > who can't afford to pay $1000+ for an O-Scope. > > Collin Douglas > > cbdougla@uokmax.ecn.uoknor.edu An apple can be made to do digital sampling up to about 5 or 10 =Hz, acting like a scope, but that's too slow for the kind of work I'm doing (10-20 MHz). Even so, if a few people mail to me to say they're interested I'll post plans for a sampling card with software. I might even be conviced to manufacture a few for the cost of parts. (after finals)
nicholaA@batman.moravian.EDU (Andy Nicholas) (12/17/89)
> An apple can be made to do digital sampling up to about 5 or 10 =Hz, > acting like a scope, but that's too slow for the kind of work I'm doing > (10-20 MHz). Even so, if a few people mail to me to say they're interested > I'll post plans for a sampling card with software. If that first term was "Mhz" then I'd be willing to bet that you could just make a card for the memory expansion slot and because that slot is addressed the full speed of the IIgs, then you could sample as fast as you'd like to be able to... It would probably be a good thing to try this on a ROM 03 GS, then at least you'd have some memory to play with and wouldn't necessarily need the memory expansion slot. If I recall correctly, at the KC Dev Conference, John Brooks was asking how to make the slots go faster, even if it meant butchering a motherboard. Rob Moore said it couldn't be done unless you used the memory slot. John needed to build a board to drive some lasers for a laser show... andy -- Andy Nicholas GEnie, AM-Online: shrinkit Box 435, Moravian College CompuServe: 70771,2615 Bethlehem, PA 18018 InterNET: shrinkit@moravian.edu
brianw@microsoft.UUCP (Brian WILLOUGHBY) (12/22/89)
> An apple can be made to do digital sampling up to about 5 or 10 =Hz, > acting like a scope, but that's too slow for the kind of work I'm doing > (10-20 MHz). Even so, if a few people mail to me to say they're interested > I'll post plans for a sampling card with software. I don't know if I've mentioned this before (and I also don't know whether you mean kHz or MHz), but I built my own custom A/D and D/A cards that are capable of 40 kHz sampling AND display, with scope-style auto-level edge-triggering display, with simultaneous average level and peak/peak hold VU display. This was at 1 MHz. At 3.58 MHz TransWarp'd speeds, its unbelievable. No, I'm not offering to build these for everyone (like another poster offered). A much better (read: useful) approach would be to have banks of RAM on a card devoted to storing incoming signals as digital values. Then the Apple could spend full time displaying the data while the card automatically did the sampling and storage. Most digital storage scopes run at sampling rates that are about 8 times faster than DRAM access speeds. The trick here is to have eight independent banks of RAM with staggered access. By cycling through the banks one at a time, each bank sees accesses at 1/8 the sampling rate. I read about this technique in EDN (I think), and the design would be much simplified by utilizing the Apple ][ power supply and CPU. Has Apple Co. ever acknowledged the awesome number of Apple ][ computers used in scientific research labs for data acquisition? Every time I turn around in a college campus lab, I see an Apple ][ Plus or //e with wires attached all over the place - hooked to monstrous machinery or measuring equipment. If Apple would recognize what I feel is a market equal to the so-called "Education" market, then their emphasis would necessarily shift to performance as it can be used for engineering applications. BTW, this kind of shift in focus would make me very happy - since I basically use my Apple ][ Plus as a home sound lab tool. Brian Willoughby UUCP: ...!{tikal, sun, uunet, elwood}!microsoft!brianw InterNet: microsoft!brianw@uunet.UU.NET or: microsoft!brianw@Sun.COM Bitnet brianw@microsoft.UUCP