Hysteresis Comparator

mind123

Hysteresis Comparator [Copy link]

 

How to calculate the two points G1 and G2 in the picture

mind123

How to calculate the circuit in Figure 2

gmchen

It is the value of the op amp output voltage divided by the two resistors at the back. Since the op amp here works in the comparator state, its output should be a value close to its power supply voltage. The specific value should be checked in the data sheet after selecting the model.

maychang

mind123 posted on 2018-1-29 14:36 How to calculate the circuit in Figure 2

Was this textbook written by the canteen chef? Take a closer look yourself, is that a hysteresis comparator?

mind123

maychang posted on 2018-1-29 15:20 Is this textbook written by the canteen chef? Take a closer look yourself, is that a hysteresis comparator?

How do you analyze it specifically?

mind123

gmchen posted on 2018-1-29 15:17 It is the value of the op amp output voltage after being divided by the two resistors behind it. Since the op amp here works in the comparator state, its output should be a value close to its...

Is there a specific calculation formula?

gmchen

The 4th poster is right, this circuit should use a hysteresis comparator, but the circuit is obviously wrong, it is an amplifier, not a comparator.

gmchen

As long as the positive and negative input terminals of the op amps in the figure are swapped, both op amps will work in the hysteresis comparator state. However, in that case, the explanations in the article are reversed. To comply with the explanations in the article, the feedback resistor needs to be connected between the op amp output and the non-inverting input terminal.

maychang

mind123 posted on 2018-1-29 15:39 How to analyze it specifically?

The output end is connected to the inverting input end of the amplifier through the variable resistor R1 (R2). This is negative feedback, but how can it be "hysteresis"?

mind123

maychang posted on 2018-1-29 16:19 The output end is connected to the inverting input end of the amplifier through the variable resistor R1 (R2). This is negative feedback, but how can it be "hysteresis"?

According to this circuit, can it be calculated?

maychang

mind123 posted on 2018-1-29 17:08 According to this circuit, can it be calculated?

According to this circuit, can it be calculated? According to this circuit, it can be calculated, but the accurate calculation is quite troublesome. Swap the amplifier's non-inverting input and the inverting input, and connect the variable resistor R1 (R2) to the amplifier's non-inverting input, and form positive feedback with the resistor marked with "battery voltage" and other resistors to divide the voltage. There can be several "other resistors", including the resistor connected in parallel with the two capacitors, the resistor that supplies power to the voltage regulator tube... and R1 and R2 will affect each other (that is, the two amplifiers will affect each other depending on their state). In addition, the two capacitors will greatly slow down the speed of the comparator flipping. Therefore, if you want to apply it in practice, it is better to modify this circuit.