DIY Scopes

  • eOscope Looks like a pretty good design? Worth studying the input stage (except, holy cats, the input impedance sucks!)
  • Large Storage Depth Oscilloscope the opposite of what I want, no prescaler.
  • Final Report Absurdly slow, 5KHz?
  • [1] Unfinished but uses the FX2. Apparently it also has a good front-end.
  • FPGA Flashy
  • [2]
  • [3] translation Good information on the front-end and has very similar performance to what I want.
  • Bitscope Appears to be a reliable and complete design but inelegant and expensive.
  • Soudez Scope Awfully comprehensive but looks well designed.
  • French Appears awfully complex.
  • Ppretty simple and cheap (35$) device based on new C8051F321 from SiLabs. It uses on-chip features like USB and memory to store and transfer samples, and external ADC. Features include logic analyzer (2.7 Mhz), oscillograph (200 kHz), logic generator (1.7 Mhz) and some others mode. Some additional features like signal filtration, protocol analysing (I2C, SPI, 1-Wire, UART) and firmware updates are available via PC GUI.
  • Oscilloscope Numerique
  • Semifluid pic-based scope.
  • Another Pic-based scope

Very Interesting

  • OWON PDS5022S 25 MHz full Benchtop w/USB, $360 $445. Looks very good.
  • Hantek DSO-2090 40 MHz USB only $200
  • PC USB Oscilloscope DiSco $170 Very cheap but sloooow.

Very Cool, Not my Bag

  • DS1000 100MHz scope + 16ch logic analyzer, $1000+,
  • The USRP (Ettus) from GnuRadio looks slick. Still, too expensive.

Not so much

  • DSO-101 Mad props for open source software!! Still, somewhat pricey.
  • bitscope. Too pricey for what you get. Sweet that they support Linux tho.
  • Pico. I like the scope-as-a-probe concept but it's just too pricey for what you get.
  • ETC M520. Boooring, expensive, no Linux.
  • Link Instruments. Super pricey, no Linux. Good performance tho. alias?
  • PoScope, $150 $200 200 ksamp/sec?? Even for the price, this is just silly.
  • HandyScope Too expensive!
  • SoftDSP
  • Elexp Some boring looking things.
  • qkits interesting, cheap. No Linux tho.
  • LabJack UE9 $430, 50KHz, a complete mess.
  • [4] (won't let me link to the product) The Swordfish has the right form factor for a change. It's too expensive though and has a tiny capture buffer. 10 bit 1 GS/s, decent for $240.

Other stuff

  • 100 MHz probes, $30/2
  • Ant16 logic analyzer, $240 too expensive, can't link to the page
  • Cool looking (opto)isolators: http://isoloop.com/ Can isolate USB signal. [www.analog.com/Analog_Root/productPage/productHome/0%2C2121%2CADUM1400%2C00.htm AD alternative] datasheet
  • Maxim's appnote on PGAs: http://www.maxim-ic.com/appnotes.cfm/an_pk/2013 and a MAX532 app.
  • Another type of PGA: Software Selectable Input Range -- i.e. the chip can accept +/-12V even though it's driven from single-ended 3.3V.
  • Good input stage using TI inst amp: OPA656 OPA657. Ouch, $6-8. That's probably too expensive. Still, ain't no way I'm going to use split signal paths.
  • Another input stage: AD8065. Claims that it can be placed immediately after scaler.
  • I don't want any aliasing or peak detection. That just adds too many parts (right?)

With the scope, must be sure that 2 channels sample exactly simultaneously. Otherwise, how can you tell if timing issues are screwing you? And how can you trigger from one signal and watch another? Is there any way to exactly sync their clocks? Yes... If we can somehow connect them using another connector.

What I Want

  • $64.00 for a single device. Basically no packaging. Order the software on CD separately for $10 or just download off the web. The manual is just a PDF and really small because it only covers the hardware.
  • 8 bit resolution, 100 sa/sec to 40 Msa/sec (user-selectable).
  • Looks exactly like a 100 MHz scope probe except maybe a little fatter (not much!) and a lot shorter.
    • Instead of a BNC connector on the end, we have a USB A connector.
    • No need for attenuation because the A/D is 1 cm from the tip of the probe and bandwidth isn't that high anyway.
  • Simple prescaler. Should probably do 50mV, 500mV, 5V, 50V, 500V? Depends on the A/D I choose.
  • The software is open source. Cross-platform (probably in C#, though wxwindows, Qt or Shoes might not be bad choices). Need to publish a strong API so people can write new software on unheard of platforms. Even the drivers should be open source.
  • Optional:
    • Floating input? Differential probe? Optoisolated? That would be AWESOME but is it too much effort?
    • A button on the side can be used for different things... Switch modes, trigger the trigger....?
    • A tri-color LED on the back that can be used to show device state. If that's too expensive
  • Interchangeable tips somehow?
    • No, probably not worth the effort. It should just be a scope probe tip, and you can just glomp something else on to bring tiny signals out to the fat probe.

Software:

  • The obvious oscilloscope. But I want to use 3D cards to show the waveform receding in time along the Z axis.
  • The obvious spectrum analyzer. Can we offload the FFT onto the graphics card?
  • A DMM, except that all we can measure is voltage.
  • If we make it differential, can sell a
  • If we combine this with a high-voltage function generator, we can measure
  • A logic probe. The PC speaker can beep low or high. It can also use TTS to read the voltage and pulse width. Hell, it can play the signal it sees.
  • Good looking Qt-based GPL DSO and DMM software.

ADC

Looks like we're going to have to go with an external programmable gain amp feeding a simple 40 MSPS ADC. I just don't see any combined ADC/PGA packages that will work. Boo.

Integrated Programmable Gain:

  • TI THS1041 $5.50 from TI, 40 MSPS, 10 bit, 3.3V dual supply, 103 mW, 900 MHz input (?), internal reference, 28 pin soic/tssop (G4 part is green).
  • TI ADS5204 $14.00 from TI 40 MSPS, 10 bit, 3.3V single supply, dual S&H inputs, differential or single-ended, 18 dB PGA, 275 mW (ouch), 300 MHz analog, internal reference, 48 pin tqfp.
  • MAX1101 $5.00 1 Msps Single Chip, 8 Bit CCD Digitizer with Clamp and 6-Bit PGA. Too slow. 5V 20mA.

Plain Old ADC:

  • TI TLC5540CPW $4.00 8 bit 40 MSPS
  • TI ads831e $8.00 Jameco Apparently a good, cheap ADC.
  • Nat ADC0820 Jameco Like $2.50, 8 bit, internal sample/hold, 75 mW max, 1.5us conversion (a little slow, looking for 15ns?), single 5V supply, no adjustment needed, no missing codes. Linearity? Over temp? DEFINITELY TOO SLOW, by 2 orders of magnitude!
  • AD9283BRS-50 $4.00
  • MAX1336/MAX1337 8 bit 5V 7 Msps, $2.00
  • MAX1196 Dual, 8-Bit, 40Msps, 3V, Low-Power ADC with Internal Reference and Multiplexed Parallel Outputs $5.00
  • MAX1193 45 Msps $3.70 Ultra-Low Power, 45Msps, Dual 8-Bit ADC
  • MAX1195 40 Msps $5.00 Dual, 8-Bit, 40Msps, 3V, Low-Power ADC with Internal Reference and Parallel Outputs
  • MAX1197 Dual, 8-Bit, 60Msps, 3V, Low-Power ADC with Internal Reference and Parallel Outputs $6.00