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 [...]

A fast peak detector similar but faster than previous peak detector, can be implemented using open loop configuration. Here is the schematic diagram of the circuit: In this  design, D1 is the detector diode and D2 is a level shifting or compensating diode. A load resistor RL is connected to – 5V 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  [...]

Thermocouples give many benefits compared to thermistor/RTD (Resistance Temperature Devices).  Some advantages of thermocouple are their wider temperature range, their reliability, and their consistency over long period of time. In some cases,  thermocouple calibration  is even unnecessary. Thermocouple temperature sensors are widely used in temperature controllers for boilers, oven,  pressurized reactor, even in high temperature [...]

Feedback in public address amplifier is something that should be avoided. The ideal solution is by adjusting the microphone and the speaker position, but it’s not always possible in many situation. Using frequency shifter to change the output frequency 10Hz lower than the input frequency can solve the problem, but it’s too expensive for [...]