Free Circuit Diagram

Graphic equalizer is a filter which it’s overal frequency response can be adjusted easily by sliding the potentiometer knob, and the potentiometer’s knob positions will naturally mimic the frequency response of the filter, and this is very user friendly. Many methods have been developed by electronic engineers to make audio equalizer, such as Baxandall’s [...]

With very low harmonic distortion, 2N4416 JFET is suitable to smoothly oscillate in a circuit. On application where low harmonic content is required for a good mixer circuit, JFET local oscillator is very good. Below is the circuit diagram of Low Distortion Oscillator: And here’s the 20 MHz Oscillator Values [...]

TDA2003 is my favorite audio amplifier integrated circuit chip in 10 Watt class. All you need is just adding few passive components and your amplifier will be ready. You can even amplify ultrasonic range if you wish to abuse its usage, just to convince you that this chip is more than enough to handle any [...]

Sine wave oscillator can be implemented using Wien-Bridge oscillator like in our previous sine wave oscillator circuit, but now we present another method of generating sine wave signal. Using phase shifter, we can build a simple sine wave generator, as shown in the schematic diagram below: Sine wave oscillator using phase shifter has [...]

Metal Detector Circuit Topology One of the simplest method of metal detecting is by beat frequency oscillator. Basically, the circuit consist of two balanced oscillator. One oscillator provides the reference signal, and other oscillator is acting as the detector element. The reference oscillator’s frequency is fix, while the detector oscillator is variable depending on [...]

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  [...]