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    EEVblog #820 – Mesh & Nodal Circuit Analysis Tutorial

    EEVblog #820 – Mesh & Nodal Circuit Analysis Tutorial

    Dave explains the fundamental DC circuit theorems of Mesh Analysis, Nodal Analysis, and the Superposition ...

    • http://upsetgames.com Sean

      You’re evil. Here it is still March 31 and you caught me off guard!!

    • http://www.flashingleds.wordpress.com Craig

      Hi Dave, is the effect very reproducible? Specifically, if you were to try this again tomorrow would you expect to see the same result?

      • http://www.eevblog.com EEVblog

        I can guarantee I’d get the same result tomorrow.

    • FreeThinker

      Nice Try,
      Just came in from a 12hr nightshift but you will have to try much harder next year, very convincing though.

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    • Tomi Leinonen

      That is amazing!! I just did show this to my friends and they were quite sceptic because today is 1st of April 😀 I really need to try that when I get home.. Too strange but stilla amazing!

    • http://www.adlerweb.info adlerweb

      And 1+4 is also 5 – Really strange 😀

    • desearcher

      If this is a wind up for April Fool’s Day, good on ya, mate!

      Should have finished off by hooking it up to a piezoelectric speaker to produce a secret message, though.

    • Zac Bailey

      I’d like a short behind the scenes of that. It was a good presentation.

    • http://www.digi-online.net masterburner

      Oh darn, you got me. I found it rather strange to design an easter egg in such a simple chip, but damn… It was very convincing. :)

    • Mav

      Hmm should I build this up and scope it …….
      Nah I know Aussies are all a bunch o larakins.

      What you should have done is engineered it to modulate at 88.8hz at 1.21 volts then dubbed the BTTF theme on the top.

      Dave no one trusts ya on april fools 😀

    • http://hitachi8.zzl.org hitachi8

      Can someone explain me how he did it?
      i suppose he recorded a wave form and played it back on the scope while faking the 555 thing.
      is that alright?

      • Edisonobilly

        not this time Dave, but a good one anyway. you sent the probes of the scope to something else, below the camera’s view, that generated the 55.5hz.

        got ya

        Dave has more than one of those scopes so the same leads from another one ran to the circuit. . . . . u get the picture

        • http://www.eevblog.com EEVblog

          No, I can assure you the leads are genuinely connected to the circuit as shown.

    • R2k

      And what happens if you are connect a speaker to that 555? Does it say “Luke, i’m your father”?

    • http://www.toddfun.com Todd Harrison

      I almost didn’t watch it cause it’s April 1st and you fooled me so bad last year. But I just had to grin and bear it. It was fun.

    • http://fazjaxton.net Kevin

      Nice one, Dave! I bought it, and am still uncertain after reading the comments. Pulling the cap with the scope in frame was a nice trick. Great discovery or great hoax either way!

    • Adam Ward

      Damn it, not a SINGLE one of that batch of ten thousand 555’s that I bought last week had this issue. I’m sending them all back for a refund.

    • John

      You got me Dave! Not until I clicked the comments did I realize that this had to be a joke. I was thinking how amazing it was that nobody had discovered this in 40 years. Very clever and elaborate joke. Kudos!

    • Tony Stark

      Last year the EEVBLOG, was going to be sold to a company, this year the 555 timer is modulationg… I can’t wait for April 1 2012

    • http://www.tectron.net mgburr

      Nice try Dave, Although you changed out the “Parallel” resistors on the bottom of the R2 resistor between shots. Also would have worked better if you used a 2.23k for R2 = SQR(5). Your Dave Cad drawing is off for values. 😛 The 200 ohm pot for “tweaking” R1 leaves the lower frequency range at 57k, The max you would get is 166 ohms because of the parallel 1k on the pot. All in all a good show mate. 😛

      • http://www.eevblog.com EEVblog

        Yes, the DaveCAD values are just nominal, I had to continually tweak them a bit during the shoot to keep the narrow adjust range I needed. No trickery in the resistor values.

        • Mgburr

          O.k. I can accept that, however what are the values for the “output filter”? If they happen to be resonant to 55.5hz, then it does make sense that they would provide a sine wave for the square wave output of the 555. Also the “capacitor” looks suspiciously close to this. http://www.oscilent.com/spec_pages/Resonators/R-630.html

          Which would give a sine wave at resonant frequency.

    • George Graves

      Damn it.

    • Ryan

      I was expecting you plugging it into a speaker at the end and getting rick rolled. You kept a straight face through the entire video, good job!

    • http://www.hackersworkbench.co.cc William Arthur

      If anyone has any doubt that this is an April Fool’s joke, I just tried it and, of course, didn’t get the same results as Dave. The video made it pretty convincing though!

    • Adam Shea

      I call ATTiny or a PIC10/12. It wouldn’t be too hard to code one up to work like that.

    • Murphy

      Somehow producing just the right conditions to pick up RF noise? 55.5ish hz is really close to the 50hz mains frequency.

      • http://www.eevblog.com EEVblog

        Close doesn’t cut it. The 50Hz mains is very precisely 50Hz. 55.5Hz is essentially a mile away.

    • Ramzi

      Maybe the Devil changed his number from 666 to 555 (lately he’s getting alot of anonymous calls), and you got his signal. LOL

      Really Dave thanks for the Sharing.

    • ac

      Well if you want to keep to the story then lets see that same modulation with 1) another brand of scope 2) with the wires visible.
      Those Agilents seem to be so advanced I wouldn’t be surprised if there was some setting to add in this signal for “educational purposes”.

    • Tom

      Even if this would be a real effect, manufacturing imperfections would result in quite a large frequency deviation, not making it 55.5 (k)hz but somewhere between 50 and 60 khz, nullifying the reference to the name.

    • http://www.oscene.net Antonio Barba (TheKaneB)

      Nice trick guy :-)

    • http://www.fxdev.org FxDev

      I like your t-shirt dude :)

      • http://www.eevblog.com EEVblog

        You can buy it in my Merch shop.

        • http://www.fxdev.org FxDev

          I know i can but here is Turkey you know shipping costs will be more than T-Shirt..

    • http://www.fxdev.org FxDev

      Damn! I like your t-shirt!

    • gw3up69bxaq0

      I think this time constant is caused by a feedback of an internal spread-capacitance.
      maybe funny, but the real funny is when theres no spectrum holes of an analog device.

    • Harald
    • Temo

      Hi Dave

      I am trying this as my first Oscilloscope Project. Can you make a better diagram of what you have (cap values and where you are actually taking the reading)

      Sorry I am a n00b and i just finish getting a old 1987 Oscilloscope

    • Alex

      I totally bought it :)

    • Riddler

      Hi! I just discovered this fantastic web site. I love the multimeters comparisons and reviews. Keep the nice and VERY USEFUL job!

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    • Michael K.

      Great try! Awesome presentation!

      I think it could be a PIC 12F675.

      1 – GND
      2 – as GP5 to GND
      3 – as GP4 output
      4 – as GP3 as input (only 😉

      5 – detecting the presence of N/C capacitor.
      6 – as GP1 to GND
      7 – as AN0 to the POT
      8 – +5V

      I have to try… 😉

    • http://cimeng.com cimengse

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    • Ivan

      I just see this today on our space mailinglist

    • Richard H.

      Hello 555 people, I was involved with incoming lot testing at a medium size computer firm in the 70’s ?i can’t recall the specifics, but we determined that there was a significant difference between 555’s made by two of the large well known semiconductor chip manufacturers! I don’t recall heat the difference was, might have been a pin out difference? Or a different function of one pin?I think there was some workaround? Either could be made to work?? Otherwise only one of the mfgrs 555 would work correctly on the board! Drove the Purchaseing people nuts! they were told by brand2 that brand2 was a drop in pin for pin equivalent!, but the board test group in the plant reported otherwise!! Please post reply with the details,if you know!

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