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2784Re: [Raspberry_Pi_4-Ham_RADIO] RE: Preparing to purchase Raspberry Pi

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  • Tim McDonough N9PUZ
    Feb 7, 2014
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      In addition to the current capability of your power supply you need to be aware of how much current your peripherals try to draw through the R-Pi. The power input line connected to the micro USB power connector has an inline PTC (polyfuse) rated at 1.1A 6VDC.

      A schematic of the R-Pi Rev. 2.0 boards is available here:

      <http://www.raspberrypi.org/wp-content/uploads/2012/10/Raspberry-Pi-R2.0-Schematics-Issue2.2_027.pdf>

      In most applications I have not needed a powered hub either. However, I do have one R-Pi on my network that has no mouse, keyboard, or wireless but it does have an external 1TB USB disk drive. I ended up using a powered hub for the drive because the disk would not always initialize and come online.

      73,

      Tim N9PUZ


      On 2/6/2014 2:33 PM, Max Harper wrote:
      The statement "You will also need an external USB powered hub for the keyboard and mouse.�� The pi USB port is limited in current." is questionable. No, you can't draw the 500ma that USB is speced for, but that usually is not the real problem. I have seven Raspi and don't use a powered hub on any of them. I have all kinds of devices connected to them. Some have un-powered hubs where I needed more ports. They are all powered with a power supply from Adafruit and I don't have the problems that I read about daily. This supply is set at 5.25V to make up for the voltage drop in the cable.
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      The Raspi should have had an onboard regulator. It would have eliminated most of the power related problems. Trying to run one off of a cheap cell phone charger that has poor regulation is where most of the problems begin. There is a difference between a charger and a power supply.
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      Max KG4PID
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