Recent content by mrkenneth

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...