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  1. R

    Caller ID stumper

    Are you sure the phone jack goes directly to the phone company instead of one of those modems that carry phone, TV and internet on one signal line and separate them within the residence? Try to get another phone that you know for sure works elsewhere, or bring your phone over to a friends house...
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    Caller ID stumper

    The id burst is sent between the first and second ring. The ring you hear on your phone is not the same ring that that the calling party hears. I have a subscription to Nomorobo, https://www.nomorobo.com/ which kills my incoming calls on the first ring if they are known to be scammers. Some...
  3. R

    Whatever happened to this product?

    I am more interested in why that product was not a commercial success. I emailed Bourns couple of days ago asking that question. Thus far, I have not received an answer. Ratch
  4. R

    Whatever happened to this product?

    I guess somebody's order got derailed. Thanks for the info. I am going to email Bourns shortly and ask them why they are not manufacturing them anymore. Ratch
  5. R

    Whatever happened to this product?

    I remember one could solder different tabs on this component and create lots of different fixed values. Then one day they disappeared from the market. Where are they now? Ratch
  6. R

    Finding a high frequency differential amplifier Transfer Function

    What's the problem? If Vd is zero, all the transistors will be conducting with 1/4 of the current source in each transistor. All the emitter voltages will be at -0.7 volts and all the E-B junctions will be forward biased. If Vcc is greater than 0.7 volts, the the C-B junction will be reversed...
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    Finding a high frequency differential amplifier Transfer Function

    Very interesting circuit. Differential amps with a current source have a very small turn on/off range. As you can see from the plot below, ±4 Vt , where Vt = 25.4 mV, is all it takes to switch the paired transistors from ON-OFF to OFF-ON. To stay in the linear region, Vd should be within...
  8. R

    Finding a high frequency differential amplifier Transfer Function

    Why don't you answer the question I asked in post #3?
  9. R

    Operational Amplifier Internal Resistance

    As others have stated, an ideal op-amp has infinite "internal" resistance. The answer for the input resistance of Vi2 is so simple as to be a "gift". Can you tell what it is? I can see just by glancing at the circuit what the input resistance of Vi1 is. Can you see how that is possible...
  10. R

    Finding a high frequency differential amplifier Transfer Function

    What do you want us to do? Do you want the equations for the voltages V1, V2, Vout/2 which you marked in red? Obviously V2 is grounded. A transfer function needs to be defined before is can be calculated (Vout/Vin,Iout,Iin,Vout,Iin,Iout,Vout). Which is it? I have never done double...
  11. R

    CURRENT FLOW vs ELECTRON FLOW

    Who says that electrons move protons in a circuit? Protons are part of the atom's nucleus and are stationary. You will be in for big trouble and confusion if you first ask what the polarity of the charge carrier is. Especially if there are both kinds of moving charges in the circuit to be...
  12. R

    CURRENT FLOW vs ELECTRON FLOW

    Electrochemistry involves the movement of positive charged carriers in a solution. So does a proton steam from an accelerator. Ratch
  13. R

    CURRENT FLOW vs ELECTRON FLOW

    And, as I said before, if the charge carriers are positive, then the calculated mathematical charge flow is the same. If the charge carriers are negative, then reverse the result from the mathematical charge flow calculation., Ratch
  14. R

    CURRENT FLOW vs ELECTRON FLOW

    It is important that you get the concept of charge carriers correct. That is why you should peruse #11 of this thread https://www.electronicspoint.com/threads/full-wave-rectifier.287940/#post-1762515 . Then, if you have any questions, just ask. Ratch
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    Question about active low pass filtering

    I would check LTspice and see what parameters they are using. My manual derivation of the Bode plot and the CAD program seem to agree with each other. Ratch
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    Question about active low pass filtering

    The peak of Vout/Vin has a peak of 44000 radians = 7 kHz. The slope drops 30 dB from 10 kHz to 50 kHz. So, 10 2^x = 50 . x = 2.32 . The slope is 30/2.32 = 12.92 dB/octave. Radians is what my plotting routine does. I have not figured out to make it do Hz yet. The peak of the CAD is 7 kHz...
  17. R

    Question about active low pass filtering

    OK, first I will do an analysis of the circuit using LaPlace transforms, and then I will check the results with a CAD program. The four simultaneous equations for the frequency analysis are as follows: The Bode plot of vout/vin is: And, the Bode plot of the CAD program is: Notice that the...
  18. R

    What is a capacitor?

    A capacitor is an electrical energy storage component that stores energy in an electric field. Irregardless of what most literature and folks say, capacitors do not become "charged". Anything that separates a charge is a capacitor. Charging a capacitor is technical slang, and describes wrongly...
  19. R

    Resistivity question help

    Calculations are straight forward. Keep the units consistent. Ratch
  20. R

    Resistivity question help

    Resistivity is an intrinsic property of a material and does not depend on the resistance value of any size or shape. In other words, a cubic foot has the same resistivity as a cubic meter of the same material. Ratch
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