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    EEVblog #1056 – Digilent Open Scope MZ Review

    Dave looks at the Digilent Open Scope MZ Review, an $89 open source oscilloscope, logic ...

    • Heck, your meter was definitely not the only thing picking up interference from the phone. Weird, wonder why it’s so sensitive.

    • Joe

      Hey Dave,

      • Damn you Joe beat me by 2 minutes

    • Ouch i never seen GSM mess something up that badly. Sure an issue that Fluke should look in to.

      Oh and Dave btw mobile phones crank up the transmitting power if you are in a spot with bad signal(Battery life thing). Also older phones seam to use higher powers.

    • Almost sounds as if the GSM signal is throwing harmonics that are near the clock signal of the Fluke firmware. I’d love to see what’s coming out of that phone on a spectrum analyzer. Sounds like inadequate bandpass filters coming out of the mixer stage. Conditions could be just right to put the firmware chip into program mode, and brick it (maybe the carrier on the phone that bricked the other meter carried the correct command string by a weird coincidence?).

    • Tilman Baumann

      In call RF power is actually lower then those beacon calls GSM phones do once in a while. They also go into high power mode when a call is received.
      GSM uses adaptive power. Putting the whole setup in a wire mesh could also give it the little extra kick to brick that baby.
      I see revision two of this test coming up. 🙂

      Anyway, great hack.

    • Al

      Actually quite a few devices are susceptible to the HF bursts caused by the TDMA nature of GSM. (The device recording Dave’s voice for instance)

      See http://www.national.com/an/AN/AN-1698.pdf for a short introduction on how this applies to op amps.

    • Tjeerd

      Next time: Hold all the phones next to the 87V.

    • Yup, I can confirm this with my 87 V as well. The meter turned off right when I made the call (the receiving end didn’t even had to pick up the phone). The distance between the phone and the meter was about 5cm or something like that. But I didn’t manage to brick mine either.

      But this is quite a disappointment. You’d think Fluke tests their meter on common RF radiation like this. I have my mobile phone and multimeter laying around on my bench all the time.

    • Just tried on my 87 III with a CDMA phone (Droid on Verizon) and couldn’t reproduce it. I’ll test again when a friend with a GSM stops by and report. I wonder if only the 85V has the problem…

    • George Graves

      Stupid American meters!!!


    • Watch out Dave, don’t think your tinfoil cap was grounded properly!

      • Eddie Hagler

        The tinfoil hat was definitely well grounded. It was in contact with a particulaly dense bit of rock. 😉

        I work in the cell phone industry. Apparently the flukes seem to be suceptable to the freqs used by the 2g spectrum.

        I wonder what effect the 4g (700 mhzs) will have on the flukes or even other meters.

        What does this say about the potential effect on other electromagneticly sensitive devices like our bodies?

    • Now that I think of it, this could be an interesting test for someone with an RF generator. If they have 87-V’s at school, I’ll see if I can drag out an RF gen and test it out.

    • G’DAY MATE!! Hey Dave!, Great test!! But, it would be awesome to take the meter appart and see wich component on that side could be causing the problem. Well, maybe would be a good oportunity to do that on the upcoming live show!!
      I’ll be looking forward to that and reminding you tomorrow!!

      See ya!!

      • CJ

        yes definitely I would love to see this one fixed. You could try using that copper tape bishop graphics makes. Place the tape over the LCD driver IC (or other components affected) and shield it to ground. The adhesive side of the copper tape is not conductive. I’ve used this method a lot as a temporary fix for RFI. It would be interesting what component is affected and why.

      • I did indeed do that on the live show, and the CD4069 and/or surrounding circuitry is the likely culprit.

    • Macpod

      Hey Dave, did you also try the GSM test with the probes attached? Sure seemed to make a difference with wifi.

    • Joe

      There’s no doubt – we all want to see it die, so that you can take it apart and see what was damaged.

    • PanicOpticon

      A similar phenomenon, this time effecting Dell laptops: http://dvlabs.tippingpoint.com/blog/2008/06/30/cellular-interference

      I’ve disassembled that style of machines and am reasonably confident that the flex cable driving the touch pad and keyboard are directly under that part of the hand rest. I’m also pretty sure that these laptops use PS2 to drive their keyboards.

      When we played around with this, we were actually able to hard lock the laptop on several different occasions.

      In our testing it also was not an issue when using 3G. Which given that 3G (UMTS) is a CDMA style spec makes sense…

    • Kodon

      Put on the probes and try to brick it with GSM.

    • Bambur

      It looks to me like Fluke’s MCU gets resetted by the GSM interference. It reveals a very bad PCB layout…

      Dave, I’ve been following your video blog for almost a year now. I have to admit I just love it! Waiting for your next episode!

    • Neil


      You might have had more luck bricking it if you had the leads plugged in when you waved your mobile around.

      When you had it near your router adding the leads made a huge differance to the pickup noise.


    • Jay

      Heard about this a while back where a cell phone turns on an oven. Really scarry! http://www.wpix.com/news/local/wpix-cell-phone-turns-on-oven,0,2237817.story

    • SK

      GSM 3G or not has no effect on my 16 year old Fluke 87.

    • Bill

      Check out this funny page from fluke:


      Hey Dave, is that your Gossen dressed up as a fairy princess butterfly? 😉

      • Funny and kinda true before the mobile phone GSM thing, but now they have to back it up by fixing the issue!

        “It could be day one on the job site. Or day 100. No matter what, it’s up to you whether you’re seen as a beginner or a pro. Show up with a Fluke

    • Chris Jones

      3G (WCDMA) and also GSM will tend to use the lowest amount of power that is needed, so that the battery life of the phone will be good and also so that they can minimise the interference when they reuse the same frequency in other cells to make best use of the spectrum that they pay big license fees to get. In the case of WCDMA, the power can range from -50dBm up to +24dBm average power. It could be transmitting 0.25 Watts or only 0.00000001 Watts, and from the user’s point of view it is hard to tell which, so it’s difficult to draw general conclusions that a product is not affected by 3G phones without knowing the power level in the test.

      By the way, I know someone whose car would not start whenever he placed his phone on the dashboard. I am always a bit wary of putting my phone near the airbag circuitry too.


    • Mike

      Ah come on guys. It might not be pretty, but even if my 800 Euro bench meter would do it- so what. Why would anybody put there cellphone next to the multimeter. If you have the problem- just work around it. I don’t own a fluke 87, but I wouldn’t actually really care about it.
      What I instead do care about, is the shitty content of this video. Basically the message could be told in 1 minute, leaving the remaining 14 minutes for an investigation of the problem! Don’t test it, take it apart and measure! I mean this just looks like it is messing with the MSP430 inside the Fluke. First it affects the connections to the display and then it triggers the reset at some point. That should be possible to test as an hypothesis.

    • Ryan

      Granted, the Fluke meter should be more robust. The Fluke 87 appears to be unusually susceptible to GSM interference and Fluke should fix that in the next revision.

      Having said that, I really, really hate GSM. GSM’s stone-age air interface with its obnoxious power envelope is the most common source of short-range RFI in the modern world. Everyone is familiar with that buzzing clicking noise that comes out of every piece of audio equipment within 5 meters of an active GSM phone. That fact alone

    • Does this problem also exist
      on the FLUKE 287 ?

    • Rich

      Hey its called the FLUKE, I guess for a reason aye?

    • At around 4:30 dave says that the line starts at about $3300. Yes the MDO3012 2 channel, 100MHz is $3350USD, $3670 AUD. But the 4 channel, 1GHz MDO3104 is $13,900 USD, $15,239 AUD! Dave has moved to the statospher

    • Tristan Pauwels

      Waar is je nummer van gsm

    • Tristan Pauwels

      You my best friend ai wil your Number

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