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Square wave generator circuit

Short answer

An op-amp astable circuit with an RC timing network and positive feedback resistor divider produces a square wave; frequency f = 1/(2RC ln[(1+β)/(1-β)]). Alternatively, a 555 timer astable gives f = 1.44/[(RA+2RB)C].

Draw the circuit diagram of square wave generator.

An op-amp astable multivibrator (relaxation oscillator) is a common square-wave generator.

            +--------[ R ]--------+
            |                     |
            |       |\            |
            +-------|-\           |
            |       |  >----+-----+---o Vo (±Vsat)
          [C]   +---|+/     |
            |   |   |/      |
           GND  +--+--[R2]---+
                   |
                 [R1]
                   |
                  GND
  • R and C form the timing network (R from the output to the inverting input, C to ground).
  • R1 and R2 give positive feedback β = R1/(R1 + R2) to the non-inverting input.
  • The output swings between +Vsat and −Vsat. The capacitor charges between ±βVsat.

Frequency: f = 1 / {2RC ln[(1 + β)/(1 − β)]}. With R1 = R2 (β = 0.5), f = 1/(2.2 RC).

Another form is the 555 timer astable circuit (RA, RB, C), which gives f = 1.44/((RA + 2RB)C).

✓ Answer checked by Claude Opus 5.5 (high effort)

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