Free Circuit Diagram

Integration is one of basic signal processing that can be done in analog domain. Using operational amplifier (op-amp), integration operation can be done with very simple circuit with very high accuracy. Here is the schematic diagram of an integrator circuit: The resistor R2 should have the same value with R1 since R2 [...]

When you switch on your amplifier, you can see your speaker pop up with high power, and it can be harmful to your speaker. To make your speaker’s life time last longer, you have to avoid such situation. You can use an electronic circuit to protect your speaker, that connect your speaker to your power [...]

Using a special purpose single IC chip LA3600, we can build a graphic equalizer with low components count.  The internal design of the chip uses transistors gyrator circuit, with connections to external capacitors to set the response. This graphic equalizer circuit is suitable for tape-recorders, radio-cassette recorders, car stereos, or home theater sound systems. You [...]

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  [...]

This pin diagram will be  useful when viewing these connectors. Sometimes you hold a soldering iron to the back of the connector, and you don’t remember the numbering of the pin. Here is the pin diagram for your reference: The number of each pins are actually  stamped on both sides of any D-type [...]

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 [...]