This is function generator using op amp. As usual the function generator will be expensive and difficult.However, this is a simple circuit with only two ICs.

This circuit is suitable for experiments. The output is 3 waveform , Square wave signal amplitude 7Vp-p, Triangular wave = 2Vp-vp and sine wave = 2Vp-p all have the frequency 1kHz.

We use 2 x LM1458 IC number, is the main equipment this a dual op-amp IC. This circuit uses op-amp 4 section, follow circuit image.

The IC1a is square wave generator, Assumed initial, C1 is charging voltage at inverting input pin to zero, Until voltage at non inverting input voltage is slightly positive.(A ratio of the op-amp output offset voltage determined by R1 and R2)

**Circuit diagram of function generator using op amp**

This time difference of the voltage input Enough to make the output of an op-amp in the volatility as a “high”.

When the output becomes high, C1 begins charging, the voltage at pin inverting, start over non-inverting input, an output swing to push down to zero.

which C1 Discharging again.

This is different from the first round, the amplifier output to an inverse alternating between low and high indefinitely. This produces a rectangular signal.

In the middle of the second op-amp. Defined as is integrator system, the input of the op-amp second is a square wave signal. The object of the first op-amp,.

The output of the op-amp is a triangle wave, whose amplitude is 2Vp-p only.

The triangular signal through op-amp 3, which determines the signal integrator, The output its image as a sine,.

Through to the fourth op-amp to amplify the signal to increase, with the inverting amplifier, the signal phase with the third op-amp.

This circuit use power supply: +9 V and-9V, IC number RC4558, or **LF353** ICs used instead.

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## kriya

15 Oct 2012what changes are required in the ckt,so as get output with variable frequency.