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  • Users: mrkenneth
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  1. mrkenneth

    Receiving raw hex or binary from serial port in Linux shell

    I am working with some AXIS network cameras (namely the AXIS 221 and the AXIS 2420). The cameras contain a web server using an ETRAX 100(LX) CRIS processor running ELinux. I can use Telnet to access the shell (mish) as root. I would like to interface a Dallas Semiconductor 1-Wire temperature...
  2. mrkenneth

    Base resistors needed for saturated transistors?

    Are resistors needed between the transistors and the PIC microcontroller in the diagram below? Each transistor will be driving a variable load (actually, multiplexed LEDs) from 0 A to 1.25 A in saturation. The LEDs are connected in series to current-limiting resistors, so the current between...
  3. mrkenneth

    500 - 3000 MHz Signal Generator

    What is the simplest circuit for generating a sine wave or a square wave from 500 up to 3000 MHz? The signal does not need to be modulated; just a simple sine wave or square wave. I would prefer the power output to be greater than -10 dBm at 50 ohms, but I can add an amplifier if needed. The...
  4. mrkenneth

    Unbalanced Sinking/Sourcing of PICs

    I know this may be a very rudimentary question, but please bear with me. Can the amount of current going into a microcontroller (more specifically, a Microchip PIC16) be different than the amount of current leaving it? I would like to connect the common anode of a LED display to the positive...
  5. mrkenneth

    Sockets for 56-pin LFCSP and/or 52-pin MQFP?

    I am thinking of using the Analog Devices ADuC847/ADuC848 microcontroller for a future project. (http://www.analog.com/en/prod/0,,762_0_ADUC847,00.html) (http://www.analog.com/en/prod/0,,762_0_ADUC848,00.html) The only packages that are available with the part are 56-pin LFCSP and 52-pin MQFP...
  6. mrkenneth

    Effects of Water on RF Circuits?

    Hopefully this is the best forum for this post... Anyway, here goes: What are the effects of water on radiofrequency circuits in the range of 500 MHz to 3000 MHz? I have been thinking about immersing an entire circuit consisting of a planar antenna and some RF circuits into some water. The...
  7. mrkenneth

    Distance between two arms of dipole

    I know this is a very trivial question, but I will ask it just for interest's sake. What should be the distance between the feedpoints of the two arms of a dipole antenna? Is it related to the frequency? Or does it even matter? How about monopoles? Thanks in advance! :-)...
  8. mrkenneth

    Connecting VCOs for generating RF signals

    I have been looking for something that can generate a RF signal from around 1 GHz to 2.5 GHz, and found that Maxim makes voltage-controlled oscillators that can be used to generate a small spectrum of frequencies. (e.g. MAX2622 and MAX2750) Can I just connect these directly to some antennas for...
  9. mrkenneth

    Ferrites before or after voltage regulator?

    I am working with some RF circuits (up to 2 GHz) and need a clean power rail. I need to reduce 5 V to 3.3 V and have everything as clean as possible. The 5 V input is powered from two Li-ion batteries and is regulated by a normal 7805. Is it better to place a ferrite before the 3.3 V LDO...
  10. mrkenneth

    Resistors before LCD logic lines

    I know this may be a stupid question, but here goes: Will a typical 8-bit parallel LCD display work if all eight of the logic lines are connected to a microcontroller (Microchip PIC) in series with 330-ohm resistors? The 330-ohm resistors are supposed to be for an LED 7-segment display, but I...
  11. mrkenneth

    Using an Op Amp to extend the voltage of a RF Detector?

    I would like to connect 8 Analog Devices AD8314 RF Detectors to a PIC16F877A microcontroller with 8 onboard 10-bit A/D convertors. The output voltages of the AD8314 RF Detectors are from 0V to around 1.2V DC, but 0.1V to 1.0V is sufficient for my use. The PIC will be powered from 5V, and since...
  12. mrkenneth

    Spiral Antenna and Baluns

    I am planning to use a spiral antenna with an RF Detector (for cellphones) using Analog Device's AD8314. The antenna currently looks like this: http://s92795644.onlinehome.us/scipho/spiral.jpg (reduced to 25% of actual size) http://s92795644.onlinehome.us/scipho/spiral2.jpg (actual size at 600...

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