## Simple Stand-Alone Voltage-to-Frequency Converter Using LM231/LM331

Using LM231/331 chip, we can build a low-cost voltage-to-frequency converter, ideal for analog-to-digital conversion, frequency-to-voltage conversion, long-term integration, linear frequency modulation-demodulation, and many other functions.  When it’s used as voltage-to-frequency converter, the output will be a pulse train with frequency linearly equal to the applied input voltage. For higher level of accuracy against temperature drift, LM231A/LM331A can be used, let’s […]

## Wien Bridge Oscillator: The Circuit Schematic Diagram and The Design Formula

The excellent high input impedance, high slew rate, and high voltage qualities of CA3140 op-amp make it suitable for Wien-bridge sine wave oscillator. The basic circuit for Wien-bridge sine wave oscillator is shown in the figure below (the upper part). You can see the formula in the figure, when R1=R2=R, and C1=C2=C, then the formula would be a very simple […]

## Square Oscillator Using Comparator: The Circuit Schematic Diagram and The Formula

Using a single supply quad comparator LM339, LM239, LM2901, LM2901V, NCV2901, or MC3302, we can build a square-wave oscillator with simple circuit and formula. Here is the schematic diagram: This circuit is suitable if you need  many square-wave oscillators in one circuit, since the quad packaged comparator provide four comparators in one single  integrated chip. [circuit’s schematic diagram source: Motorola […]

## Function Generator Using CA3080 and CA3130 Op-Amps

The schematic diagram shown in the figure below show a function generator circuit using CA3130 in the integrator the threshold detection sections. Both triangular and square-wave signal are available from this circuit’s output, ranging from 0.1Hz to 100KHz (1:1000000 ratio). This frequency adjustment is done only by a single control R1. A voltage control input is available for externally-controlled frequency […]