Free Circuit Diagram

This FM transmitter circuit is small, similar to our previous single chip FM  transmitter, but this FM transmitter is monophonic. You can see in the circuit’s schematic, the left and right signals is mixed before modulate the radio frequency. Here is the schematic diagram of the circuit:   The core of this [...]

For anyone who love transistor circuits, here you can find small wattage discrete amplifier. Building discrete amplifier is much more fun and some people say it’s involve more artworks than building the ones with integrated circuit. Look at the figure below for the circuit’s schematic diagram. A variable resistor 470 Ohm is provided [...]

Electric motor has been widely used as motion control, and many  type of motor controllers  have been designed to provide variable speed drives for the motor. The best controller is the servo controller, where a precise speed control is implemented using a speed sensor in the feedback path.  The circuit of the motor controller in [...]

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 [...]

LM386 is one of my favorite small audio amplifier integrated circuit chip. The LM386 is a power amplifier designed for use in low voltage consumer applications. The inputs are ground referenced while the output automatically biases to one-half the supply voltage. The gain is internally set to 20 to keep external part count low, [...]