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Circuit fantasist
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Rather it resembles a bilateral diode limiter... but in no case it is a Schmitt trigger because there is no positive feedback... there is only a negative feedback in an inverting configuration.

Well, let's try to see what the basic idea is behind it, and to analyze its operation (please, participate in this explanation).

First we see an inverting amplifier (R1 = R7 = 100 k and the op-amp) with a gain of -1. For now we do not understand why R3 is connected not just in the output of op-amp... but maybe later we will understand. Also, for now, we do not understand what is the role of the resistor R2 = 50 k... but maybe we will understand this later ... just we should not be discouraged:)

Then we see two voltage dividers: R3,R4 - connected between the op-amp output and the positive rail; R5,R6 - between the op-amp output and the negative rail. It seems their outputs produces reference voltages (thresholds) for the series diode limiters.

The diodes are virtually grounded. So, when the input voltage is between the two thresholds they are off... there is a virtual ground... and the circuit is an inverter (Vout = -Vin).

Now imagine the input voltage increases enough so the output voltage of the upper voltage divider R3,R4 goes down below the zero. The upper diode isturns on and diverts the input current directly into the op-amp output... so the output voltage stops changing... and this is the high threshold.

Similarly, if the input voltage decreases enough so the output voltage of the lower voltage divider R5,R6 goes up above the zero, the lower diode isturns on and diverts the input current directly from the op-amp output... so the output voltage stops changing... and this is the low threshold.

Note that always there is a negative feedback (througheither through R7, or the upper or lower diode)... and the op-amp never saturates.

But I still can't understand what is the role of the resistor R2 (50k). One explanation can be that it "helps" the input source passing an additional current from/to the ground...

Rather it resembles a bilateral diode limiter... but in no case it is a Schmitt trigger because there is no positive feedback... there is only a negative feedback in an inverting configuration.

Well, let's try to see what the basic idea is behind it, and to analyze its operation (please, participate in this explanation).

First we see an inverting amplifier (R1 = R7 = 100 k and the op-amp) with a gain of -1. For now we do not understand why R3 is connected not just in the output of op-amp... but maybe later we will understand. Also, for now, we do not understand what is the role of the resistor R2 = 50 k... but maybe we will understand this later ... just we should not be discouraged:)

Then we see two voltage dividers: R3,R4 - connected between the op-amp output and the positive rail; R5,R6 - between the op-amp output and the negative rail. It seems their outputs produces reference voltages (thresholds) for the series diode limiters.

The diodes are virtually grounded. So, when the input voltage is between the two thresholds they are off... there is a virtual ground... and the circuit is an inverter (Vout = -Vin).

Now imagine the input voltage increases enough so the output voltage of the upper voltage divider R3,R4 goes down below the zero. The upper diode is on and diverts the input current directly into the op-amp output... so the output voltage stops changing... and this is the high threshold.

Similarly, if the input voltage decreases enough so the output voltage of the lower voltage divider R5,R6 goes up above the zero, the lower diode is on and diverts the input current directly from the op-amp output... so the output voltage stops changing... and this is the low threshold.

Note that always there is a negative feedback (through R7, the upper or lower diode)... and the op-amp never saturates.

But I still can't understand what is the role of the resistor R2 (50k). One explanation can be that it "helps" the input source passing an additional current from/to the ground...

Rather it resembles a bilateral diode limiter... but in no case it is a Schmitt trigger because there is no positive feedback... there is only a negative feedback in an inverting configuration.

Well, let's try to see what the basic idea is behind it, and to analyze its operation (please, participate in this explanation).

First we see an inverting amplifier (R1 = R7 = 100 k and the op-amp) with a gain of -1. For now we do not understand why R3 is connected not just in the output of op-amp... but maybe later we will understand. Also, for now, we do not understand what is the role of the resistor R2 = 50 k... but maybe we will understand this later ... just we should not be discouraged:)

Then we see two voltage dividers: R3,R4 - connected between the op-amp output and the positive rail; R5,R6 - between the op-amp output and the negative rail. It seems their outputs produces reference voltages (thresholds) for the series diode limiters.

The diodes are virtually grounded. So, when the input voltage is between the two thresholds they are off... there is a virtual ground... and the circuit is an inverter (Vout = -Vin).

Now imagine the input voltage increases enough so the output voltage of the upper voltage divider R3,R4 goes down below the zero. The upper diode turns on and diverts the input current directly into the op-amp output... so the output voltage stops changing... and this is the high threshold.

Similarly, if the input voltage decreases enough so the output voltage of the lower voltage divider R5,R6 goes up above the zero, the lower diode turns on and diverts the input current directly from the op-amp output... so the output voltage stops changing... and this is the low threshold.

Note that always there is a negative feedback (either through R7 or the upper or lower diode)... and the op-amp never saturates.

But I still can't understand what is the role of the resistor R2 (50k). One explanation can be that it "helps" the input source passing an additional current from/to the ground...

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Circuit fantasist
  • 19.5k
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  • 71

Rather it resembles a bilateral diode limiter... but in no case it is a Schmitt trigger because there is no positive feedback... there is only a negative feedback in an inverting configuration.

Well, let's try to see what the basic idea is behind it, and to analyze its operation (please, participate in this explanation).

First we see an inverting amplifier (R1 = R7 = 100 k and the op-amp) with a gain of -1. So farFor now we do not understand why R3 is connected not just in the output of op-amp... but maybe later we will understand. Also, for now, we do not understand what is the role of the resistor R2 = 50 k... but maybe we will understand this later ... just we should not be discouraged:)

Then we see two voltage dividers: R3,R4 - connected between the op-amp output and the positive rail; R5,R6 - between the op-amp output and the negative rail. It seems their outputs produces reference voltages (thresholds) for the series diode limiters.

The diodes are virtually grounded. So, when the input voltage is between the two thresholds they are off... there is a virtual ground... and the circuit is an inverter (Vout = -Vin).

Now imagine the input voltage increases enough so the output voltage of the upper voltage divider R3,R4 goes down below the zero. The upper diode is on and diverts the input current directly into the op-amp output... so the output voltage stops changing... and this is the high threshold.

Similarly, if the input voltage decreases enough so the output voltage of the lower voltage divider R5,R6 goes up above the zero, the lower diode is on and diverts the input current directly from the op-amp output... so the output voltage stops changing... and this is the low threshold.

Note that always there is a negative feedback (through R7, the upper or lower diode)... and the op-amp never saturates.

But I still can't understand what is the role of the resistor R2 (50k). Maybe youOne explanation can? be that it "helps" the input source passing an additional current from/to the ground...

Rather it resembles a bilateral diode limiter... but in no case it is a Schmitt trigger because there is no positive feedback... there is only a negative feedback in an inverting configuration.

Well, let's try to see what the basic idea is behind it, and to analyze its operation (please, participate in this explanation).

First we see an inverting amplifier (R1 = R7 = 100 k and the op-amp) with a gain of -1. So far we do not understand why R3 is connected not just in the output of op-amp... but maybe later we will understand. Also, for now, we do not understand what is the role of the resistor R2 = 50 k... but maybe we will understand this later ... just we should not be discouraged:)

Then we see two voltage dividers: R3,R4 - connected between the op-amp output and the positive rail; R5,R6 - between the op-amp output and the negative rail. It seems their outputs produces reference voltages (thresholds) for the series diode limiters.

The diodes are virtually grounded. So, when the input voltage is between the two thresholds they are off... there is a virtual ground... and the circuit is an inverter (Vout = -Vin).

Now imagine the input voltage increases enough so the output voltage of the upper voltage divider R3,R4 goes down below the zero. The upper diode is on and diverts the input current directly into the op-amp output... so the output voltage stops changing... and this is the high threshold.

Similarly, if the input voltage decreases enough so the output voltage of the lower voltage divider R5,R6 goes up above the zero, the lower diode is on and diverts the input current directly from the op-amp output... so the output voltage stops changing... and this is the low threshold.

But I still can't understand what is the role of the resistor R2 (50k). Maybe you can?

Rather it resembles a bilateral diode limiter... but in no case it is a Schmitt trigger because there is no positive feedback... there is only a negative feedback in an inverting configuration.

Well, let's try to see what the basic idea is behind it, and to analyze its operation (please, participate in this explanation).

First we see an inverting amplifier (R1 = R7 = 100 k and the op-amp) with a gain of -1. For now we do not understand why R3 is connected not just in the output of op-amp... but maybe later we will understand. Also, for now, we do not understand what is the role of the resistor R2 = 50 k... but maybe we will understand this later ... just we should not be discouraged:)

Then we see two voltage dividers: R3,R4 - connected between the op-amp output and the positive rail; R5,R6 - between the op-amp output and the negative rail. It seems their outputs produces reference voltages (thresholds) for the series diode limiters.

The diodes are virtually grounded. So, when the input voltage is between the two thresholds they are off... there is a virtual ground... and the circuit is an inverter (Vout = -Vin).

Now imagine the input voltage increases enough so the output voltage of the upper voltage divider R3,R4 goes down below the zero. The upper diode is on and diverts the input current directly into the op-amp output... so the output voltage stops changing... and this is the high threshold.

Similarly, if the input voltage decreases enough so the output voltage of the lower voltage divider R5,R6 goes up above the zero, the lower diode is on and diverts the input current directly from the op-amp output... so the output voltage stops changing... and this is the low threshold.

Note that always there is a negative feedback (through R7, the upper or lower diode)... and the op-amp never saturates.

But I still can't understand what is the role of the resistor R2 (50k). One explanation can be that it "helps" the input source passing an additional current from/to the ground...

added 71 characters in body
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Circuit fantasist
  • 19.5k
  • 2
  • 24
  • 71

Rather it resembles a bilateral diode limiter... but in no case it is a Schmitt trigger because there is no positive feedback... there is only a negative feedback in an inverting configuration.

Well, let's try to see what the basic idea is behind it, and to analyze its operation (please, participate in this explanation).

First we see an inverting amplifier (R1 = R7 = 100 k and the op-amp) with a gain of -1. So far we do not understand why R3 is connected not just in the output of op-amp... but maybe later we will understand. Also, for now, we do not understand what is the role of the resistor R2 = 50 k... but maybe we will understand this later ... just we should not be discouraged:)

Then we see two voltage dividers: R3,R4 - connected between the op-amp output and the positive rail; R5,R6 - between the op-amp output and the negative rail. It seems their outputs produces reference voltages (thresholds) for the series diode limiters.

The diodes are virtually grounded. So, when the input voltage is between the two thresholds they are off... there is a virtual ground... and the circuit is an inverter (Vout = -Vin).

Now imagine the input voltage increases enough so the output voltage of the upper voltage divider R3,R4 goes down below the zero. The upper diode is on and diverts the input current directly into the op-amp output... so the output voltage stops changing... and this is the high threshold.

Similarly, if the input voltage decreases enough so the output voltage of the lower voltage divider R5,R6 goes up above the zero, the lower diode is on and diverts the input current directly from the op-amp output... so the output voltage stops changing... and this is the low threshold.

But I still can't understand what is the role of the resistor R2 (50k). Maybe you can?

Rather it resembles a bilateral diode limiter... but in no case it is a Schmitt trigger because there is no positive feedback... there is only a negative feedback in an inverting configuration.

Well, let's try to see what the basic idea is behind it, and to analyze its operation (please, participate in this explanation).

First we see an inverting amplifier (R1 = R7 = 100 k and the op-amp) with a gain of -1. So far we do not understand why R3 is connected not just in the output of op-amp... but maybe later we will understand. Also, for now, we do not understand what is the role of the resistor R2 = 50 k... but maybe we will understand this later ... just we should not be discouraged:)

Then we see two voltage dividers: R3,R4 - connected between the op-amp output and the positive rail; R5,R6 - between the op-amp output and the negative rail. It seems their outputs produces reference voltages (thresholds) for the series diode limiters.

The diodes are virtually grounded. So, when the input voltage is between the two thresholds they are off... there is a virtual ground... and the circuit is an inverter (Vout = -Vin).

Now imagine the input voltage increases enough so the output voltage of the upper voltage divider R3,R4 goes down below the zero. The upper diode is on and diverts the input current directly into the op-amp output... so the output voltage stops changing... and this is the high threshold.

Similarly, if the input voltage decreases enough so the output voltage of the lower voltage divider R5,R6 goes up above the zero, the lower diode is on and diverts the input current directly from the op-amp output... so the output voltage stops changing... and this is the low threshold.

Rather it resembles a bilateral diode limiter... but in no case it is a Schmitt trigger because there is no positive feedback... there is only a negative feedback in an inverting configuration.

Well, let's try to see what the basic idea is behind it, and to analyze its operation (please, participate in this explanation).

First we see an inverting amplifier (R1 = R7 = 100 k and the op-amp) with a gain of -1. So far we do not understand why R3 is connected not just in the output of op-amp... but maybe later we will understand. Also, for now, we do not understand what is the role of the resistor R2 = 50 k... but maybe we will understand this later ... just we should not be discouraged:)

Then we see two voltage dividers: R3,R4 - connected between the op-amp output and the positive rail; R5,R6 - between the op-amp output and the negative rail. It seems their outputs produces reference voltages (thresholds) for the series diode limiters.

The diodes are virtually grounded. So, when the input voltage is between the two thresholds they are off... there is a virtual ground... and the circuit is an inverter (Vout = -Vin).

Now imagine the input voltage increases enough so the output voltage of the upper voltage divider R3,R4 goes down below the zero. The upper diode is on and diverts the input current directly into the op-amp output... so the output voltage stops changing... and this is the high threshold.

Similarly, if the input voltage decreases enough so the output voltage of the lower voltage divider R5,R6 goes up above the zero, the lower diode is on and diverts the input current directly from the op-amp output... so the output voltage stops changing... and this is the low threshold.

But I still can't understand what is the role of the resistor R2 (50k). Maybe you can?

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Circuit fantasist
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Circuit fantasist
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Circuit fantasist
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Circuit fantasist
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  • 24
  • 71
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