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  1. D

    Input impedance and Max RMS ac voltage

    When you overdrive the input on a frequency counter, does the display not stable, display is random? Also when using banana red and black banana wires from a function generator to a frequency counter, can this pickup 60 cycle hum and other radio interferences causes the counters display to not...
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    Calculating gain in this op amp stage

    I'm confused what resistors are Rin and what resistors are Rf? R114 does nothing for the gain formula?
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    Input impedance and Max RMS ac voltage

    So the input resistance and the max voltage RMS has nothing in relationship? Isn't all bench equipment that is 50ohms always 5 volts RMS? and 75 ohms is 10 volts RMS? Its standardized to this for all bench equipment
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    Calculating gain in this op amp stage

    Is R117 and R115 = R in? R116 = Rfeedback? or is R116 and R115 = R feedback? Or is R114 and R115 = R in? C38 with R117 is a filter, but some of the voltage is going to pin#3 and Pin#2 C38 voltage divides the input signal to R117 So this is a differential gain stage?
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    Input impedance and Max RMS ac voltage

    50 ohms = Max 5 volts RMS But why does 50 ohms have a max 5 volt RMS? how did they get this 75 ohms = Max 10 volts RMS Why does 75ohms have a 10 volt RMS? 1K ohm = Max 15 volts RMS Why does 1K ohms have a max 15 volt RMS? 1 Meg ohm = Max 20 volts RMS Why does 1 meg ohm have a max 20...
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    Calculating gain in this op amp stage

    The input voltage is 8.8 vdc going to R117 U12 pin#6 output voltage is 4.4 vdc How do you calculate the gain? What does C38 do? What kind of gain stage is this called? it's weird how they arranged Rin and the feedback RF Plus the signal and voltage is going to both inputs , so it's some kind...
  7. D

    DVM meter capacitance mode has internal battery?

    But the internal batterys voltage is what? to measure a capacitor? also what is the internal diode for when measuring the diode? The Internal battery has a higher test voltage for capacitors? and the internal diode in the capacitance mode does what?
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    Input impedance and Max RMS ac voltage

    Bench Equipment have different input and output impedance and Max RMS voltage 50 ohms = Max 5 volts RMS 75 ohms = Max 10 volts RMS 1K ohm = Max 15 volts RMS 1 Meg ohm = Max 20 volts RMS How did you get the RMS voltage? without knowing the current? What happens when you put a higher AC voltage...
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    DVM meter capacitance mode has internal battery?

    When using a DVM meter to measure capacitors In Capacitance mode there is an internal battery and a Diode? What is the diode used for and how does the diode get damaged? The internal battery needs to be changed, but the internal battery is only used for measuring capacitors Fluke 87
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    Universal Counter is not stable with a load why?

    Yes on the O scope , the frequency and voltage is good The problem is that the Universal counter display is not stable, displaying the frequency is jumping around random only when it's loaded or hooked up to the circuit , under test
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    Meg ohm resistors , are opens circuits?

    sorry u feel that way , just trying to learn
  12. D

    Meg ohm resistors , are opens circuits?

    True, I agree So you're saying that the stage after it can changes it's voltage, current, resistance and it won't affect the previous stage because the Meg ohm resistor stabilizes the previous stage The Meg ohm resistors is in series on the output of an Op amp, this helps stabilize the...
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    Meg ohm resistors , are opens circuits?

    So what does these Meg ohm resistors do? they just reduce the feedback voltage or current from other parallel branches or parallel paths? but why reduce it? The Meg ohm resistors stablize the feedback voltage from drifting out of tolerance?
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    Universal Counter is not stable with a load why?

    Why doesn't this circuit work in square waveform? only works in sine waveform The frequency is 10 hz input Is Capacitor C13 blocking the low frequency Square waveform? Is that why the circuit works only with a sine waveform What does U1 , Q7, Q8 do? is this a draining off the voltage...
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    Universal Counter is not stable with a load why?

    I use these Universal counters HP5315B Universal Counter HP5334B Universal Counter I'm using a Ling Function generator for a waveform generator Sine waveform at low frequencies I use the Universal counter to display a digital readout of what the frequency is of the sine waveform When I...
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    Meg ohm resistors , are opens circuits?

    R110 ( 2 meg ohm resistor ) blocks the voltage and current of output U12 and goes to another output point R113 ( 4.99 Meg ohm resistor ) blocks like an open switch from current and voltage looking back These resistors are called isolation resistors
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    Meg ohm resistors , are opens circuits?

    Some techs call them "isolation resistors" when current or voltage is "looking back", the Meg ohm resistors are like an open switch or isolate the stage Take a look at the schematic
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    Meg ohm resistors , are opens circuits?

    So Meg ohm resistors in series set the output impedance? i thought only meg ohm resistors in parallel do. what is the difference from a Meg ohm resistor in series compared to a meg ohm resistor in parallel. They both set up the impedance but what is the difference between the two configurations?
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    Meg ohm resistors , are opens circuits?

    In general, what you guys have seen on schematics of Meg ohms resistors in series do what? The ones I see is on the output pin of a op amp, its not the Feedback resistor or Rin resistor to the op amp , its on the output pin in series
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    In rush chokes on op amp inputs

    servos and synchros have an AC output with a phase angle Does the AC output has noise and ripple riding on it?
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