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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?

    Thank you Yashu! Using those would make my project so much easier and even reduce the cost! One of the TPIC costs less than eight discrete transistors/FETs, and I save the resistors too! Why is the TPIC listed under the category of Temperature Sensors and Control ICs? The ICs seem better suited...
  3. mrkenneth

    Base resistors needed for saturated transistors?

    Thank you itsmoked! Very useful data! Too bad Microchip does not include these characteristics in their 300+ page datasheets. The voltage drop is more than I expected... I guess the curve would be similar for the DIP package and for the low output. What happened after 25 mA? :-P Thanks again...
  4. mrkenneth

    Base resistors needed for saturated transistors?

    Sorry, the actual part number of the microcontroller is PIC16F687 (datasheet: http://ww1.microchip.com/downloads/en/devicedoc/41262a.pdf) You are right about the clamp diode to Vdd and to Vss! I guess I will have to power the PIC from the same 5-V supply as the LEDs. Thank you cbarn24050 for...
  5. mrkenneth

    Base resistors needed for saturated transistors?

    Thank you for all of the suggestions! I have looked at some MOSFETs, but found that using a gate voltage of only 3.3 V would result in a very low drain-source current. In the end, I am using sisif's recommendations of using Darlington transistors. Actually, I plan to use Darlington NPN...
  6. mrkenneth

    Base resistors needed for saturated transistors?

    Thanks for the analysis cbarn24050. I was interpolating Figure 6 for the Vce value too... Perhaps I will have to reduce the LED current... The LEDs will be off most of the time, so I guess they would dim when all of them turn on? The datasheet for the PIC says that the leakage current is +/-1...
  7. mrkenneth

    Base resistors needed for saturated transistors?

    Thank you for all the advice. I am not able to run the PIC off 5 V, unfortunately, because all of the pins are used so I am using the regulated 3.3-V rails as the reference for the onboard A/D convertor. I should have been more detailed and clear in describing my application in the original...
  8. mrkenneth

    Base resistors needed for saturated transistors?

    Thank you all for the information. I have not had to work with transistors much. (IRstuff, I have learnt to use electronic components through their destruction. :-P) The reason I thought the transistors could be connected directly to the microcontroller pins was because the emittor of the first...
  9. mrkenneth

    Base resistors needed for saturated transistors?

    To turn the transistor off, can I TRIS the port pins to inputs, so that the pins would present a high-impedance to the transistor and thus not sink any current? The datasheet says the maximum Vbe is 5V... I guess the low output of the PIC would be around 0.6V because of the high current? How...
  10. mrkenneth

    Need to mount surface mount parts

    Wow! Now we are trying to inhale fumes? The no-clean solder that I use seems to be odourless... This is what I used, but is now obsolete at Digikey: I do not see any noticable residue after soldering either. As for the desoldering braid, I bought it for under $2.00 CAD for a 1.5-metre roll...
  11. 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...
  12. mrkenneth

    Need to mount surface mount parts

    itsmoked, I use the exact same soldering station as you for SMD work! Even the same tip! [2thumbsup] I will try a blade-shaped tip when I have time. :-) Somehow I find the odour of the water-soluable fluxes quite offensive... I like to use no-clean flux solders, and I save the cleaning time...
  13. mrkenneth

    500 - 3000 MHz Signal Generator

    I am just building this for fun, and will probably only produce one or two of these circuits. I can only make this on double-sided FR-4 printed circuit board, so I am not sure whether I can use frequencies as high as 10 GHz without much loss... Would using multiple VCOs to cover the entire...
  14. mrkenneth

    500 - 3000 MHz Signal Generator

    Thank you for the explanation. Where can I find such a VCO that generates such high frequencies? I have not seen any over 3 or 4 GHz... Are there other methods? What do commercial signal generators use? Thanks in advance! --------------------------------------------------------- Operation...
  15. mrkenneth

    500 - 3000 MHz Signal Generator

    Thanks to all for the quick replies! I still do not quite understand the concept behind how a small change in the VCO frequency can produce a large change in the output frequency of the mixer. If the mixer takes the difference of the two inputs, would not a change in one of the inputs result in...
  16. 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...
  17. mrkenneth

    Unbalanced Sinking/Sourcing of PICs

    Thanks for all of the information. The current will probably be much less than 200 mA, but I will have to check the brightness of the LEDs first. Each of the pins will sink less than 25 mA, so I don't think I will use transistors. (Don't want to add too much complexity to the project.) 2V is...
  18. 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...
  19. mrkenneth

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

    Thank you all for the information! I will not be require the microcontroller to do to much (except to acquire analogue signals and send them to a computer), so I think I will base my application on the Analog Devices 8052 microcontrollers (with the stewpid lower case letters :-))...
  20. mrkenneth

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

    Thank you both for the replies. I guess my primary reason for switching is to learn to use a different microcontroller. :-) I had wanted to try some of Atmel's offerings, but I stumbled across Analog Devices' microcontrollers, and they were too difficult to resist. I guess I also want to learn...

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