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  1. 2

    BJT Ramp?

    I don't know op amps! For now, I am pretty sure this can be done with transistors please! Can anyone please help me with the collector feedback circuit as posted to acheive the ramping specs. Thanks all in advance!
  2. 2

    BJT Ramp?

    hi, vs will be a signal from a dac output with a certain ramp frequency. so the timing is taken care of by the ramping signal. vs will start at 2vdc and ramp up to 2.5Vdc. in contrast, at the output I need 1.0 v dc to 0.5vdc. thanks
  3. 2

    BJT Ramp?

    Hello, I am pretty new to trasnsistors and lately I had calculated a ramping circuit using a simple Pn2222 transistor. When the input was 2.0VDC at the base, Vc was 1VoltDC. As the input to the base voltage ramped up towards 3.3 VDC, Vc ramped down to 0.5VDC. Therefore, this circuit had a gain...
  4. 2

    TLC7226 data sheet?

    Hello, A problem I have is interpreting what the spec sheet is really saying... please consider the following!!!! Referring to the TLC7226 part and its spec sheet at: http://www.ti.com/lit/ds/symlink/tlc7226.pdf If you go to p.4 of the data sheet and look for: ri(ref) Reference input...
  5. 2

    Emitter bias feedback with REE?

    http://www.allaboutcircuits.com/vol_3/chpt_4/10.html If you scroll down almost to the end where they speak about Boltzmann konstant.... Hope this helps Sent from my iPhone
  6. 2

    Emitter bias feedback with REE?

    Hi steve, Man oh man! did I learn this the hard way!! LOL! Thanks for your help! r
  7. 2

    Emitter bias feedback with REE?

    Hi Steve, You mean: Rb = ß[vcc-vbe / Ie - REE - RE] Rb = 300[(10 - 0.616/ 1.01ma) - 25.7 -492] Rb = 2632016 ohms then: Ie = (Vcc-Vbe) / (Rb/ß) + REE + RE Ie = (10-0.616) / (2632016 ohms/300) + 25.7 +492 Ie = 1.01 ma I can never get it as per calculations LOL.... Now with a beta of 300 I...
  8. 2

    Emitter bias feedback with REE?

    Hi Steve, It seems that the Hfe of this transistor is between 35 and 300. Here is the spec sheet: http://www.onsemi.com/pub_link/Collateral/PN2222-D.PDF However, I measured the Hfe for this particular transistor and it is 156! But what I don't understand is the difference between the...
  9. 2

    Emitter bias feedback with REE?

    Hello, I have been experimenting with emitter bias feedback method for biasing a transistor. Please locate in the following link: When I did the circuit and calculated it with the typical values as shown in attachment T2-EBF-A.png (left side), the Ie calculated value was 0.101 ma but when...
  10. 2

    Kernel or Off the shelf OS?

    Hi Steve, So for a development kit that would help me get started with Linux or android on Arm MCU which would you recommend? http://store.atmel.com/CBC.aspx?q=c:100122 or...
  11. 2

    Kernel or Off the shelf OS?

    >Look here for a list of open source hardware (many of those which run Linux). They will >also give you an idea of the hardware requirements and should have schematics and >BOMs (or should that be BsOM). Sorry Steve, unfortunately I don't see your link ! Perhaps I would go with an ARM...
  12. 2

    Kernel or Off the shelf OS?

    Yes but I don't think RPI will hand out the schematics and BOM.... I need bare bones integrity. I have to build from the ground up since there will be other circuitry added onto my board r
  13. 2

    Kernel or Off the shelf OS?

    Hi Steve, Thanks for helping me out with this. Another issue though is if I go with one of these off-the-shelf OE'es: 1- What MCU/CPU is requirements to run a minimal version of the OS? Also what would be the typical cost of the MCU/CPU? 2- How much ram/rom do these OS's require to run...
  14. 2

    Kernel or Off the shelf OS?

    Please Steve, don't feel obligated to read the following articles! O don't want you to waste your time on my account ! It's just that it makes me wonder.... what happens if Linux decides to go closed platform one day! http://lowendmac.com/musings/10mm/open-vs-closed-platforms.html...
  15. 2

    Kernel or Off the shelf OS?

    You know what jackorocko !!!! I don't trust anyone! And I mean no one. http://wiki.osdev.org/Licensing After having read this, now I am even more confused. I am not a lawyer, I don't understand all the legalities but one thing is for sure, if I do it myself it's mine. If I use OSes...
  16. 2

    Kernel or Off the shelf OS?

    It has not been tested on the field yet. But it has undergone thousands of in-lab tests. So let me ask you something. If I am using one of em off-the-shelf OSes (let's take Linux as an example) and I need to make a specific algorithm for some sort of sensor and the algorithm I come up with...
  17. 2

    Kernel or Off the shelf OS?

    Hi guys, I see. And you are 1000% sure there are no other contractual constraints with Android and Win Mob ? In all due respect, in a small embedded system how many things do we really need. In my small kernel I have created the following: - several commands to display pics and I cons - a...
  18. 2

    Kernel or Off the shelf OS?

    Hello, I am facing a crutial decision. If you are an experienced programmer or a project manager for a big IT/Electronics firm, your feedback would be very appreciated. Let's say your firm is developping a product with a *similar potential* of sales as the Iphone. However, the product I am...
  19. 2

    Power factor

    -------------------------------------------------------------------------------- Hello forum, I have been reading some lectures in this site and I have a question about obtaining the apparent power, true power, reactive power and the power factor of an actual AC circuit. Basically I am...
  20. 2

    General question about storing graphics!

    Hi saradalton, Yes, but what I am trying to say here, is that I need to be able to resize graphic (or fonts for that matter) at ****run time***** within the MCU. So it goes like this: The MCU loads a picture or a character font from flash. Then resizes it (Notice here... I need it...
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