Free Circuit Diagram

RJ45 is used to connect Ethernet port on your computer. There are two configuration: straight and cross. Straight RJ45 cables should be used to connect between computer and device such as switch or hub, and cross RJ45 cables should be used in computer-to-computer connection.  Some hub or switch has the capability to detect the cable [...]

This is a video tutorial about RJ45. This video shows how to punch down an RJ45 keystone jack using a impact tool. The first thing that we gonna do is strip the wire. It is very important because when we connect the wire, it can cause the problem. And then, put the wire on RJ45, [...]

The function of this circuit is similar with the hum filter in our previous circuit, but it use transistors instead of op-amps. It uses BC109 transistors, but any low noise high gain type will be suitable. This hum filter is adjustable via trimmer pots to fine tune it’s notch depth.   The figure below shows [...]

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 [...]

Effect on the system’s time-domain response is a common problem when designing lowpass filters. The system may fail to recognize significant changes in time because pushing the cuttoff frequency lower slows the step response. The circuit below is presented to solve the problem: On this circuit diagram, lower [...]

A second order filters can be constructed using LC (inductor-capacitor) passive circuits,  and they have been implemented for radio frequency for cheap and simplicity. For audio frequency range, unfortunately the size for the inductor and capacitor become too large, space consuming, and the most important is they’re really expensive. Because of this, active filter is [...]