Free Circuit Diagram

Notch filter is known as band-cut filter or band-reject filter. The fuction of this filter is to remove some frequency portion of a signal. The schematic diagram of this filter circuit, a second order notch filter is depicted in the figure below. The formula is actually complicated, but by taking the R3=R4 and [...]

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 [...]

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  [...]

You might be familiar with passive crossover network installed inside your speaker box, consist of inductors and capacitors. The problem with passive crossover network is that they dissipate the audio power, so it’s not environmentally friendly, contributing a little disaster of global warming.  Moreover, the capacitor and the inductor in the passive crossover network contribute [...]

This is pressure sensor signal conditioning circuit. It is simple and inexpensive circuit because it has small geometry and simple pressure sensor. It just uses a single Operational Amplifier. This circuit obtain power from from 3-V battery. To work properly this circuit must work in  0 C to 50 C temperature range. Here is the [...]

The circuit’s schematic diagram shown in the figure below is a flicker noise generator, an implementation of flicker noise analog modeling presented in NBS technical note #604, “Efficient Numerical and Analog Modeling of Flicker Noise Processes” by J.A. Barnes and Stephen Jarvis, Jr. With the component values shown the schematic diagram,  the circuit will give [...]