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An unusual Oscilloscope phenomenon

Discussion in 'Hobby Electronics' started by David L. Jones, Jun 25, 2009.

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  1. Joerg

    Joerg Guest

    Oh, I am not worried at all :)

    But I am concerned about what happens when guys like you and I are in
    their 90's, the hands are shaky, the mind ain't what it used to be and
    the senior living place doesn't allow a Tektronix mainframe in the
    rooms. The next generation doesn't have anough analog engineers.
     
  2. Joerg

    Joerg Guest

    Bad focus but shows the concept, when I was a teenager I made almost
    everything in wood, nicely polished, several layers of laquer, some more
    polishing:

    http://www.analogconsultants.com/ng/images/oak2.jpg

    I usually spent a lot more time on the enclosures than on the
    electronics but the stuff is still working.
     
  3. Jim Thompson

    Jim Thompson Guest

    Won't matter. We'll all be deep into communal despair :-(

    ...Jim Thompson
    --
    | James E.Thompson, P.E. | mens |
    | Analog Innovations, Inc. | et |
    | Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
    | Phoenix, Arizona 85048 Skype: Contacts Only | |
    | Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
    | E-mail Icon at http://www.analog-innovations.com | 1962 |

    Think things are bad now? Wait until Obama "takes care" of you.
     
  4. Joerg

    Joerg Guest

    Once I took off on a Europe flight out of SFO and the antenna top stuck
    out of the clouds while the rest of the tower was in the white. Picture
    perfect, and I had my camera in the overhead <aargh>. I could still bite
    myself, that opportunity never came again.

    Yesterday I had my comeuppance WRT to the Instek GDS-2204 scope that I
    thought is so much better than Tektronix. In many ways it is, and also
    doesn't have the nasty conducted emissions on the probe cables. But when
    debugging 74MHz gear I could not figure out where a weird buzz was
    coming from. Until I turned off the scope ...
     
  5. Joerg

    Joerg Guest

    But:

    We used such transceivers in multi/multi type ham radio contests and
    field days. There you had to deal with another 100W transmitter blasting
    into an antenna maybe 100ft away. You could make a light bulb glow on
    the other antenna. Many transceivers fell off the rocker there, the only
    ones that always performed were the super-expensive Collins line and the
    Heathkit at the budget end of the price scale. If their signal
    management wasn't up to snuff this would never have worked.
     
  6. Tim Williams

    Tim Williams Guest

    All the more money for me. ;-)

    Tim
     
  7. Tim Williams

    Tim Williams Guest

    My Heathkit IO-103 scope is the same way.

    Tim
     
  8. Two coaxial shields with one end of each grounded at opposite ends is
    pretty nice.



    Best regards,
    Spehro Pefhany
     
  9. Joerg

    Joerg Guest

    I didn't go that far but I polished and stained the corners until you
    couldn't really see where things butted up anymore.

    Saw a contractor commercial lately about the Fein Multimaster. Drooling
    all over the place. Fein is "the" electric tool company in Germany, only
    the good stuff. You had to call a 1-800 number to find out the price and
    that should have been a dead give-away. Well, found it on the Internet,
    saw the prices of spare inserts and decided that I do not need it this
    urgently.

    http://www.amazon.com/Fein-MultiMaster-FMM-250Q-Top/dp/B000U8S3QA

    That's the other thing I built, or partially had built when I was around
    15, size 6ft by 4ft and extremely sturdy (boat anchor proof). I made a
    drawing of the frame and asked my parents whether it was ok to get some
    metal stock, borrow a welding transformer and weld it in the garage. Oh
    no, no dice. So I went to the local HW store, a larger kind of mom and
    pop place. My classmates said they'd laugh at me there. The foreman took
    a look, "Yep, will be ready in two days, then we'll drive up there and
    chuck the frame over the hedge and you come down here to pay us the 70
    Deutschmarks". They didn't even want up front cash. Oh, now my chest
    swelled and I felt like an engineer. Until I glued the formica onto a
    panel that would become the top and I had it slightly skewed ...
     
  10. Rich Grise

    Rich Grise Guest

    I guess nobody told you about the shims. ;-)

    Cheers!
    Rich
     
  11. krw

    krw Guest

    Fein is simply crazy expensive. I looked at their routers over the
    weekend. I wasn't impressed, for 4X what a Bosch or PC costs. Bosch
    has a "Multi-Master type tool ("Multi-X", I think) that's a lot
    cheaper and looks just as good (Li-Ion battery, though). A little
    lower down the line, Dremmel has a copy for $100ish. If you want to
    go cheap, HarborFreight has one for $40. The reports are decent,
    acknowledging that it's a $40 tool. The only real complaint is that
    the blades loosen.
     
  12. Joerg

    Joerg Guest

    No shims. The trick is to lay the Formica upside down onto the floor,
    butter it up with glue, then lay the wood piece on top. While doing the
    latter it slipped my hand and ... thud, landed on the Formica. Almost
    perfectly line up. With the emphasis on "almost". There was no way to
    get this off because it was the Henkel Pattex type glue which never lets
    go of anything.
     
  13. krw

    krw Guest

    How do shims fix a skewed veneer?
     
  14. Joerg

    Joerg Guest

    Alright! Thanks. I guess I do have to check out Harborfreight.

    No, the HW store closed. The usual, the 3rd generation drove it into the
    ground :-(
     
  15. Joerg

    Joerg Guest

    The $40 version will be good enough for me. I've used Fein drills, they
    are really top notch. I think grampa's drill in the garage is a Fein.
    About 100 years old, works like a champ.

    [...]
     
  16. Steve Sousa

    Steve Sousa Guest

    Hello:

    Since you're into it, why don't you compare the refresh rate of digital vs
    analog scopes?
    Also known as the waveforms-per-second capability? It's something i'm very
    curious about in practice, and also, do the digitals behave as the analogs
    (like a low-pass filter) when you increase the freq of a wave-form or
    suddenly start aliasing?

    Thank you.
    I really enjoy your blog

    Best Regards
    Steve Sousa
     
  17. Phil Allison

    Phil Allison Guest

    "Steve Sousa"
    ** Be like comparing chalk with cheese.

    ** Pretty meaningles with analogue scopes that show the input signal
    continuously.

    ** Digital scopes SAMPLE the signal, both in amplitude and time - then
    show you one screen's worth of SAMPLEs.

    Bit later they show you another one.

    Bit like tasing a pot of stew with your little finger.

    ** The topic of " aliens " with DSOs is verboten among makers and fanatics
    alike.

    Plain fact is that you do not get to see what is actually coming down the
    probe cable and you may well see stuff that is not there at all.

    Bit of a worry, really.


    ...... Phil
     
  18. ehsjr

    ehsjr Guest

    Brings back pleasant memories. I donated my HW101 to the Boy Scouts
    radio club many years ago. I wish I still had my HW 16 - lots of wee
    hours CW with that (my first) rig.

    Ed
     
  19. krw

    krw Guest

    But it's ugly orange. ;-) I think I'll spring for the Bosch. I want
    to rip up some bamboo flooring and inlay a hearth in front of our
    fireplace. I can't figure out another way to make the cuts against
    the wall.

    I now have seven cordless drills (will likely give one to my son). I
    just bought a little Bosch 12V Li-Ion to match the impact driver. 100
    years ago a cordless drill was a brace and bit. ;-)
     
  20. It's not only about waveforms-per-second, it's also about the capture and
    display engine as well.
    The manufactuers have various technologies (e.g. Tek Digital Phosphor) to
    make their digital scopes have an "analog type" display and response, and
    they work superbly. In fact they can be better than analog in many respects.
    But that performance costs money, so you have to start paying around say the
    $5K mark before you get a digital scope that really performs like an analog
    one in terms of variable display intensity, response time, and capture
    dead-time.
    See here for more info:
    http://www.tek.com/products/oscilloscopes/dpo_technology/
    http://www.tek.com/Measurement/App_Notes/Technical_Briefs/55-13757/eng/55w-13757-0.pdf

    Lower end scopes don't have these "analog like" display technologies, so
    then "waveforms-per-second" is pretty much the basic benchmark. Modern
    scopes are pretty darn good though, and even the low end cheap ones are
    streets ahead of previous generation DSO's.
    Those who haven't used a modern high end digital scope don't know how superb
    they can really be.

    With modern fast real-time deep memory scopes, aliasing is pretty much a
    thing of the past.

    Might make an interesting future blog...

    Dave.
     
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