Schmidt Trigger Help: OP07 Comparator Circuit Design

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Discussion Overview

The discussion revolves around designing a Schmidt comparator circuit using an OP07 operational amplifier, focusing on the specifications of power supply voltages of +/- 12V and switching thresholds of +1V and -1V. Participants are exploring the calculation of voltage saturation and resistor values necessary for the circuit design.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant expresses difficulty in understanding how to calculate voltage saturation and its implications for determining resistor values in the Schmidt trigger circuit.
  • Another participant suggests referring to the op amp data sheet for information on saturation voltage and proposes using a resistor with two Zener diodes to set a custom saturation voltage.
  • A different participant recommends using both power supply voltages effectively by connecting resistor configurations that adjust the trigger points symmetrically around 0V.
  • A participant reiterates the initial question about voltage saturation and circuit design, welcoming the original poster and suggesting the use of separate power supply sources for clarity.

Areas of Agreement / Disagreement

Participants present various approaches and suggestions regarding the circuit design, but there is no consensus on the best method to calculate voltage saturation or the optimal resistor values. The discussion remains unresolved with multiple competing views.

Contextual Notes

Participants have not fully defined the assumptions regarding the circuit configuration, and there are unresolved steps in the calculations related to voltage saturation and resistor selection.

revird163
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Poster has been reminded to post schoolwork in the HH forums and use the HH Template in the future
I have been been trying to search forums and figure out the following question that I just cannot seem to get my head around!

Design a Schmidt comparator circuit based on an OP07 operational amplifier with the following characteristics: Power supply Voltages: +/- 12V Switching thresholds +1V, -1V

I have been trying to figure out the voltage saturation and then using this to find the resistor values for the schmidt trigger. I cannot work out what the voltage saturation is and how to calculate it at all.

Any help would be appreciated, I am really not the best at electronics!

The following is the circuit I am trying to use modeled on LTSpice:
upload_2015-11-12_14-37-44.png
 
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Consider that you have both +V and -V available since they're powering the op amp. You can tie the bottom of your R1 to -V rather than ground, and add another resistor of the same size as R1 to tie the + input to +V as well. Then tinker with your R2 value to adjust the total spread of the triggers. By symmetry the trigger points should lie on either side of the midpoint between +V and -V, or in other words, 0 V.
 
revird163 said:
I have been been trying to search forums and figure out the following question that I just cannot seem to get my head around!

Design a Schmidt comparator circuit based on an OP07 operational amplifier with the following characteristics: Power supply Voltages: +/- 12V Switching thresholds +1V, -1V

I have been trying to figure out the voltage saturation and then using this to find the resistor values for the schmidt trigger. I cannot work out what the voltage saturation is and how to calculate it at all.

Any help would be appreciated, I am really not the best at electronics!

The following is the circuit I am trying to use modeled on LTSpice:
Welcome to the PF.

I would make the power supply rails using two separate sources. Otherwise their relationship to ground can be ambiguous... :smile:
 

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