Help for a circuit schematic explanation

[nikosg1]

http://imageshack.us/photo/my-images/685/variablegaincontrol.png/"can someone please explain me the circuit schematic that i have attached because i can't understand it.

Thank youhttp://imageshack.us/photo/my-images/685/variablegaincontrol.png/

 

[SteamKing]

I can't understand your circuit because it is not attached to the OP.

 

[Bob S]

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

 

[skeptic2]

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.

 

[alphy]

Sure, I would be happy to help explain the circuit schematic you have attached. This is a variable gain control circuit, which means it is used to adjust the gain or amplification of a signal. The circuit consists of several components, including a variable resistor (labeled "R"), two capacitors (labeled "C1" and "C2"), two transistors (labeled "Q1" and "Q2"), and a power supply (labeled "Vcc").

The variable resistor (R) is connected to the base of transistor Q1. This resistor allows you to adjust the amount of current flowing into the base of Q1, which in turn controls the amount of current flowing through the transistor. This controls the amplification of the signal coming into the circuit.

The two capacitors (C1 and C2) are connected in parallel to the collector and base of Q1. These capacitors help to stabilize the circuit and prevent any unwanted oscillations or noise.

The two transistors (Q1 and Q2) are connected in a common emitter configuration, with the collector of Q1 connected to the base of Q2. This configuration allows for the amplification of the signal. The output of the circuit is taken from the collector of Q2.

The power supply (Vcc) provides the necessary voltage for the circuit to function. It is connected to the collector of Q2 and serves as the positive reference for the circuit.

Overall, this circuit allows for the control of amplification by adjusting the variable resistor. As the resistance of the variable resistor changes, the amplification of the signal will also change. I hope this explanation helps to clarify the circuit for you. Let me know if you have any further questions.