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  1. O

    Impedance of two stage amplifier

    The Electrician, Not sure why R1 shouldn't be there in the denominator? Since we're calculating Av, the overall voltage gain, we need to convert the current source to a voltage source by doing Vin=Iin*R1 in series with R1, or am I confusing something again? Then, I assumed Iin*R1=Vin and divided...
  2. O

    Impedance of two stage amplifier

    dorke, The Electrician, Thank you for your posts, helped me a lot! Now, For the overall current gain, Ai, I came up with 33.8 ~ 34.
  3. O

    Impedance of two stage amplifier

    Ok, but if you need to do a KVL to find the current ib can you just assume the voltage on R1 is Vin, or do you have to do the transformation first making a V source of value Iin*R1 in series with R1. Only then do the KVL and find the ib? What happens is you end up with Iin*R1 in the numerator...
  4. O

    Impedance of two stage amplifier

    Now, the question is how can we find Ai without converting the current source into a voltage source? Do we need to do that always? If not, what is the procedure for finding Rin, Rout, overall gain, when there is a current source for a BJT? Circuits are hunting me back... :)
  5. O

    Impedance of two stage amplifier

    Both are valid models for the BJT:
  6. O

    Impedance of two stage amplifier

    Correct, indeed the question asks for the overall current gain, Ai.
  7. O

    Impedance of two stage amplifier

    Hello guys, thanks for the helpful feedback! The problem is to always see the input impedance of stage 2 as the load of stage 1 regardless. I'm posting my solution to the problem at hand just to finish it off and I also have a couple other questions coming o_O My 2nd question is about the ckt...
  8. O

    Impedance of two stage amplifier

    Hello, I need a clarification regarding the overall gain of multi-stage amplifier and finding equivalent resistances seen by capacitors. Let's consider the ckt below: When I tried to figure out the overall gain, Av as: I considered RL1 as R11 + R10; however, from the solutions my answer is...
  9. O

    Cup with heat awareness

    These are the rechargeable batteries we're using: http://www.amazon.com/gp/product/B00JHKSMJK?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00 Would it be cumbersome to take apart the USB adapter and grab leads connecting from the wireless receiver to adapter? Also, what is the constant...
  10. O

    Cup with heat awareness

    Yes, here's the USB transmitter - http://www.ebay.com/itm/QI-Wireless-Charging-Charger-Pad-For-iPhone-Samsung-Galaxy-S5-LG-Nexus-Nokia-/111424148317?var=&hash=item19f165935d:m:mJbPtsuazPh8BEsZ27jC1XA USB adapter -...
  11. O

    Cup with heat awareness

    Hello guys we need help building a cup that would notify drinkers of hot beverages of the temperature via LEDs. Namely, if the liquid is hot - red light, warm - yellow light, cold - green. The trouble is how to power the circuit. We are not allowed to use lithium-ion batteries, only Ni-Mh...
  12. O

    Simulating in Pspice

    Hello, I'm trying to simulate a common source with and without a capacitor and for some reason get awkward results. The current shown leaving the source is 0, how can that be? Also, the current and voltage on the load are zero. I need to find out the overall gain of the ckt, Av, the input...
  13. O

    Zener diode

    Ok, understood. Thank you!
  14. O

    Zener diode

    Harald Kapp, It's just a simple ? If that's the case then the slope seems a bit too high... For instance, the first section is 572.92 and the 2nd is 19814.8,
  15. O

    Thevenin voltage

    It doesn't say directly in the statement but it's assumed that the plot should include it. I'm just not sure about that transition from breakdown to forward, does the polarity on the Vd0 and Vz0 change so that current flows + to - in tandem with the signal polarity?
  16. O

    Zener diode

    I'm having trouble understanding how to find the slopes in this circuit: Problem statement: The PWL model for the Zener diode in the circuit above is shown below. The source is a triangle wave, as shown below. Sketch the voltage across the Zener diode. Indicate voltage levels of both the...
  17. O

    Thevenin voltage

    Thank you for your help! This is what I came up with in simulation... Also, please let me know if I have the polarity set up correctly for both the forward bias and breakdown regions: 1) In the upper set output voltage, Vz, is positive and the graph rises above 0 2) In the bottom...
  18. O

    Thevenin voltage

    Hello, I need help with figuring out the open circuit voltage in the circuit below. Namely, the question is asking to plot Vz(Vs) and in order to do that we need a series circuit where the Zener diode is our load. However, when I go to verify my answer with the solutions, the Vth value is wrong...
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