Help for a circuit schematic explanation

Click For Summary

Discussion Overview

The discussion centers around the interpretation of a circuit schematic related to variable gain control. Participants seek to clarify the function and components of the circuit, exploring its theoretical and practical implications.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant requests an explanation of the circuit schematic, indicating a lack of understanding.
  • Another participant notes that the circuit image was not attached, which contributes to the confusion.
  • Some participants propose that the circuit could be a voltage comparator with significant hysteresis or an inverting amplifier with reversed inputs.
  • Another viewpoint suggests that the circuit resembles a Schmidt Trigger, explaining its behavior in maintaining output states based on input voltage thresholds and the role of the variable resistor in adjusting these thresholds.
  • A specific formula for calculating the threshold voltage is provided, contingent on the values of certain resistors in the circuit.

Areas of Agreement / Disagreement

Participants express differing interpretations of the circuit's function, with no consensus reached on its exact nature or purpose. Multiple competing views remain regarding the circuit's classification.

Contextual Notes

The discussion lacks a visual reference to the circuit schematic, which may limit the accuracy of interpretations. Additionally, the calculations and assumptions regarding resistor values and their impact on threshold voltages are not universally agreed upon.

Who May Find This Useful

Individuals interested in circuit design, operational amplifiers, or those seeking clarification on variable gain control circuits may find this discussion relevant.

nikosg1
Messages
2
Reaction score
0
Last edited by a moderator:
Engineering news on Phys.org
I can't understand your circuit because it is not attached to the OP.
 
It looks like either a voltage comparator with a LOT of hysteresis, or an inverting amplifier with gain, where the positive and negative inputs are reversed.

Bob S
 
It looks like a Schmidt Trigger. The output voltage adds to the input and maintains the output at either the + or - rail even with small variations in the input voltage. There is both a positive and negative threshold at which the Schmidt Trigger will change state. They are the input voltages that will cause the voltage at pin 3 of the opamp to cross zero volts. Since R62 is a variable resistor and can be varied between 0 and 10K ohms the threshold voltage can be varied a little. To find the threshold voltage use this formula. (Vcc/(R55 + R62))*R54. For the values given and R62 at 0 ohms, 5K ohms and 10K ohms the thresholds would be 15V, 7.5 V and 6 volts respectively.
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 17 ·
Replies
17
Views
2K
Replies
10
Views
2K
  • · Replies 15 ·
Replies
15
Views
6K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 18 ·
Replies
18
Views
3K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 16 ·
Replies
16
Views
2K
  • · Replies 30 ·
2
Replies
30
Views
4K