Amplifier Circuit DiagramsOscillators Circuit Diagramsvoltage converter

Triangular Wave Oscillator with Sine Wave Converter Schematic Circuit Diagram

This design resulted from the need for a partial replacement of the well-known 8038 chip, which is no longer in production and therefore hardly obtainable. An existing design for driving an LVDT sensor (Linear Variable Differential Transformer), where the 8038 was used as a variable sine wave oscillator, had to be modernized. It may have been possible to replace the 8038 with an Exar 2206, except that this chip couldn’t be used with the supply voltage used. For this reason, we looked for a replacement using standard components, which should always be available.

Triangular Wave Oscillator with Sine Wave Converter Schematic Circuit Diagram

In this circuit two opamps from a TL074 (IC1.A and B) are used to generate a triangular wave, which can be set to a wide range of frequencies using P1. The following differential amplifier using T1 and T2 is configured in such a way that the triangular waveform is converted into a reasonably looking sinusoidal waveform. P2 is used to adjust the distortion to a minimum.

The third opamp (IC1.C) is configured as a difference amplifier, which presents the sine wave at its output. This signal is then buffered by the last opamp (IC1.D). Any offset at the output can be nulled using P3.

The TL074, TL074A, and TL074B are high-speed JFET input single operational amplifiers. Each of these JFET input operational amplifiers incorporates well-matched, high-voltage JFET and bipolar transistors in a monolithic integrated circuit. The devices feature high slew rates, low input bias and offset currents, and low offset voltage temperature coefficients.
  • Wide common mode (up to VCC+) and differential voltage range
  • Low input bias and offset current
  • Low noise en = 15 nV/ √Hz (Typ)
  • Output short-circuit protection
  • High input impedance JFET input stage
  • Low harmonic distortion: 0.01% (typical)
  • Internal frequency compensation
  • Latch-up free operation
  • High slew rate: 16 V/µs (typical)
TL074 Applications

TL074 can be used for the construction of the following circuits:

  • voltage follower
  • Unity gain inverting amplifier
  • bilateral current source
  •  AC/DC converter
  •  instrumentation amplifier
  •  square wave generator
  •  voltage comparator
  • Power supplies
  • oscillators
  • half-wave rectifiers

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