Recent content by mp3car

  1. M

    Wood/Glass/Metal Seeking a cheap wide mouthed jar capable of withstanding a vacuum

    I believe this was performed on people by a group of scientists in China, they did it to humans and it became a museum exhibit that toured around the US under a cloud of suspicion that the subjects used were tortured/executed political prisoners…. Anyone else remember that, or get a chance to...
  2. M

    Electrical DIY Central Vacuum: Build Your Own Unit & Reduce Cost

    In my original example, I intended to convey that these two 120V motors would be internal to one "device" that is plugged into one 240V, with each motor pulling 120 from its own individual leg, similar to my example of a 240V appliance that will pull 120V from one of the legs to operate part of...
  3. M

    Electrical DIY Central Vacuum: Build Your Own Unit & Reduce Cost

    Thanks for the input... So you're suggesting wiring a two-pole breaker and break the tab to separate the duplex outlets of a normal duplex recepticle, and then have two power cords coming out of the unit? That would work too, if that's allowed per code (splitting a duplex outlet such that the...
  4. M

    Electrical DIY Central Vacuum: Build Your Own Unit & Reduce Cost

    Codes really apply more to facility wiring rather than things you plug into an outlet. For example, you can't put a 14g wire in the wall on a 20A CB, but you can plug a device with even something as small as an 18g wire into a 20A circuit, maybe even 20g. In my case, the circuit breaker in the...
  5. M

    Mixing Ground Connections For 120V AC and 24V DC

    FYI, airplanes have numerous voltages, but all share the airframe as the ground... 115VAC 400Hz and 60Hz, 28VAC 400Hz, and 28VDC. The 28VDC is created from Transformer Rectifier Units (TRUs) fed from the 3-phase 115VAC. Neutral and ground are both connected to the airframe relatively close to...
  6. M

    Electrical DIY Central Vacuum: Build Your Own Unit & Reduce Cost

    So, I know this isn't entirely an Engineering question, but I am an EE and I wanted to get a few opinions on my planned project. I have had a central vacuum in the past three homes I have owned. I have always installed the unit and all plumbing myself, but the units are still $500-$1000 just...
  7. M

    How do animals have better immune systems than humans?

    I think I know what the OP is getting at, but I am just talking about pets... I had one cat for 19 years, and have had dogs all my life. They very rarely get "sick" the way we get sick (coughing, diarrhea, vomiting, fever, etc). Whenever they do, it seems to be because they "got into...
  8. M

    Ambient air has an odor after removing respirator

    I have noticed that after wearing a respirator (dual-cartridge activated charcoal by 3M) for an hour or so, when I remove it, the ambient air smells slightly sweet, almost like slight hint of ozone. After a little while without it, the smell seems to "go back to neutral" or nothing unique. I...
  9. M

    Magnetic Resistance Exercise Bike Theory Question

    Not sure this adds a whole lot, but perhaps it will add something... My elliptical machine uses a magnetic resistance setup, it's pretty simple. When you "pedal" the elliptical, it spins an iron flywheel, and there is a semi-circular (maybe about 6" long) permanent magnet that is positioned so...
  10. M

    LNA Gain vs SNR: Can Increasing Gain Reduce Sat Tx Pwr?

    If you have a satellite that is transmitting at X dbm to a ground station, will increasing the gain of your LNA allow the satellite to use less transmit power? It seems like you'd have to improve the SNR in order to increase BER or Eb/No... If you just increase gain of the LNA, then yes, your...
  11. M

    Oklahoma earthquakes, seismography

    It's pretty sad when I can't say how close a reported location of a specific EQ is from my house without practically giving away my address...
  12. M

    Micrometeorite caught on camera in Oklahoma?

    I later found a video where two local professors claimed it was likely a meteor... HOWEVER, those professors are not very well accredited to be weighing in on this subject; one holds a BS in Meteorology (ironically, doesn't make them an expert on meteors, despite the name), and the other one...
  13. M

    Micrometeorite caught on camera in Oklahoma?

    http://www.koco.com/news/flying-object-caught-on-koco-5-news-in-the-morning/31751658
  14. M

    Oklahoma earthquakes, seismography

    @davenn: I am familiar with nyquist (I'm an EE), but I am not familiar with the highest frequency that I need to reproduce on the scope, but see you said 10 Hz, so the scope is plenty fast enough... It will do 1GS/s down to 50S/s. It will record up to 2500 data points, so at a 5s/div, one...
  15. M

    Oklahoma earthquakes, seismography

    Uh oh... that's all I need, to become MORE obsessed with them ;) My o'scope does have single trigger and hold, but it bases the sample rate on the time scale... In other words, if the time scale is 10ms/div, a 60hz sine wave (line voltage) is pretty much a perfect sine wave. however, if I do...
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