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    EEVblog #1022 – Finding A $50 Oscilloscope On Ebay

    Another look at finding a $50 analog oscilloscope on ebay. Forum HERE Podcast: DownloadBe Sociable, ...

    • Sławek T.

      The thermal parts are just awesome! Congrats to the producers 🙂


      Magnetic bubble memories…takes me back!! July 4 1983 I joined a company called Beaver Machine Tools. The company was using many controls but I remember the FANUC controls at the time used magnetic bubble memories!! These controls were very reliable and our CNC machines were sold to companies such as Rolls Royce and Pratt and Whitney. This was in the day when we still used the black punched tape to back up and load programs into the control. If anyone wonders why FANUC controls have REWIND and PUNCH etc, its because of the black punched tape. 🙂

    • Devad

      Bubble memory. Wow did that bring back some memories (pun intended). Upon returning from Army to my civilian job at a large computer firm I was put on a staff developing bubble memory. As you said it didn’t last long maybe 6 months and integrated technology surpassed what bubble was suppose to do. Dave, really enjoy you videos.
      Dave, this is somewhat off subject but I have a question.
      I’m looking of an oscilloscope but have a low budget may be $100 to $150. Sort of looking at the USB scopes that connect to a laptop for the display. The good thing I’m not looking for giga hertz bandwidth. Probably 1 to 10 MHz would be fine but has to have dual channels. Velleman has a wide range of USB scopes 150 to 500+ dollars. Not sure why someone would but a USB scope for 500 bucks. You could get a fairly good bench scope for that kind of money. Also looked at the DPscope (from Germany). It has dual channel, comes with software support for data logging and real time FFT and bandwidth of >1Mhz. (specs at http://www.pdamusician.com/dpscope/features.html)
      The kind of stuff I do now a days does not need much bandwidth. I’m working on a smart controller for my septic tank aerator. The aerator motor comes on for 10 mins and off for 50…then repeats 24/7. The problem is I don’t know if it’s actually working. I’d like to get a split transformer to measure the motor AC current and send the data via bluetooth to my desktop. Initially just seeing a current every hour would help. However I think I could also
      do some analysis on the starting current and running current changes over time. Maybe help predict failure. If the pump does not run for several hours it locks up. A new motor
      cost $500. It’s an oil fill system.
      If you have any suggestions I’d appreciate it.
      BTY – I have an old Tektronics sampling scope, I swap it for a bench scope. Know anyone that collects Tektronics. stuff.

    • Anders Oleson

      According to this site: http://www.wylie.org.uk/technology/computer/bubblmem/bubblmem.htm the numbers printed on the bubble memory chip may be a mask or map of bad “loops” that should not be used. The 7110 datasheet found on that same page does not directly say. It does tell us that the 7110 is made up of 4 “quads” of 80 loops each. The number of bits in the hex string is 4 bits/char * 16 chars * 5 rows = 320 bits so that matches exactly the total number of “loops” in the part, so it seems very plausible. Apparently the “boot” loop can be read to obtain the same information.

      These parts are non-volatile. I wonder if you can still wake it up and read from it?

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