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  1. dorke

    Why drop in voltage in this circuit ?

    Angy, Why are you using 20V ? ...that is a very "strange" value to use. Isn't there a 9v or 12V in your "circuit".
  2. dorke

    Are tantalum caps sometimes used as a circuit protector ?

    If I understand correctly the 1uF tantalum is placed at the output of the 12V regulator. How far away from the regulator is this tantalum cap placed? If indeed on the output, the way you "fixed" the board is wrong. i.e. you degraded the regulated 12V voltage of the circuit. It may work,like you...
  3. dorke

    2 transistor circuit input output question.

    Not necessarily so...;) As we say in my places(translated) Be careful, You may not see the forest for the trees...:rolleyes:
  4. dorke

    2 transistor circuit input output question.

    It looks so much more complicated this way. a note: You use the notation Vab ,it is a bit confusing,since that notation normally means the voltage between a and b. I think you should have used Vb instead. I didn't check the Zth expression...too long;) And, Yes, for Rs not zero we have to take...
  5. dorke

    2 transistor circuit input output question.

    Obviously that is true but, surly you can see it is absolutely trivial. I copy from #60: Vth=Vab=Vs*[R2/(R1+R2) - R4/(R3+R4)] That is the general case, including the Trivial("extreme") case you talk about, which isn't actually a bridge anymore. The "Formula" enables us to find the Max...
  6. dorke

    2 transistor circuit input output question.

    ??? go a head,show it .
  7. dorke

    Intel Server Mobo S3200SH Dreaded 3 Beeps!

    Try it then. I think without a working RAM it will not be possible. As far as I know, the CPU will copy from the USB to the RAM and from there to the BIOS chip. But even before that how would the USB device work without a proper driver loaded?
  8. dorke

    2 transistor circuit input output question.

    Of course I said...it is in the formula in #60. Your observation is trivial ,not interesting, and more than that meaningless.
  9. dorke

    Help! Reading Voltage with Arduino

    Yes,defiantly the input to an arduino A/D shouldn't be negative and shouldn't exceed 5V(if I'm not mistaken). Don't think the formula you are using is correct as it is.
  10. dorke

    Help! Reading Voltage with Arduino

    Well, Yes the DMM measurement is not correct for sure! It is 10Hz to 10Mhz range in frequency measurement only. but in ACV only 45Hz to 400Hz ! Use a SCOPE or If your lab has any true RMS DMM use it. The AM-510 is not good for taking this measurement!
  11. dorke

    Intel Server Mobo S3200SH Dreaded 3 Beeps!

    You probably can. But how would you load it to the faulty one? Is this the old socket type EPROM board?
  12. dorke

    Intel Server Mobo S3200SH Dreaded 3 Beeps!

    I would check all the voltages on the board with a DMM. Could be a PS failure or an on board Capacitor failure.
  13. dorke

    Help! Reading Voltage with Arduino

    You have a few problems here they are related to the AM-510 multimeter: 1.You are using a square wave, since your DMM isn't a true RMS one you are getting an error in the reading. 2.The signal you are using is 1Khz which is higher than the max frequency of 400Hz your DMM can handle. To remedy...
  14. dorke

    Intel Server Mobo S3200SH Dreaded 3 Beeps!

    here is the manual of the server. The 3 beeps code is indeed a memory problem. Are you using the correct DIMMs according to the manual?
  15. dorke

    2 transistor circuit input output question.

    Yes that is correct. But still ,being a Voltage Source the internal resistance should be very low relative to the "load" connected to the power supply. In any case we can do a transformation from delta to Y and do an accurate calculation like so: for "small" Rs : For Ra,Rb we can chose any pair...
  16. dorke

    2 transistor circuit input output question.

    Of course ±Vs is the trivial case for a maximum. But it is also a non-interesting one since this isn't a bridge any more just 2 resistors in parallel connected across Vs . The interesting case is R1~=R2 and R3~=R4. i.e. "almost or about" a balanced bridge.
  17. dorke

    2 transistor circuit input output question.

    Calculating Rth. We replace the voltage source Vs with it's internal resistance Like so: for simplicity and demonstration we redraw the circuit like so: Rs is moved ,the connection is the same. Again for demonstration we redraw like so: Now we note that Vs is an ideal voltage source thus...
  18. dorke

    2 transistor circuit input output question.

    Let us do a demonstration of how the Thevenin Theorem simplifies the calculation of the classical Loaded Wheatstone bridge(an important "tool" in many areas). We want to know all aspects of the Load and "Driving Network" and the relationship between them. Here is the circuit: We could do...
  19. dorke

    2 transistor circuit input output question.

    I would put it this way: A step required to calculate Rth is : Independent Voltage or Current Sources are replaced by their internal resistances. For an Ideal Voltage source(like we assume normally) the internal resistance is zero For an Ideal Current source(like we assume normally) the internal...
  20. dorke

    2 transistor circuit input output question.

    RL Voltage and current
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