Free Circuit Diagram

PWM can be implemented using FPGA, and this video explains how to implement a PWM counter in FPGA.

Stepper motor controller is needed to run a stepper motor, since a stepper motor cannot work by just connecting it to a power supply.  To program a stepper motor to make a complex movement, we usually need a micro controller. Fortunatelly, for a simple movement like just rotating eith a constant speed, we can use [...]

The frequency formula of 555 oscillator is popularly known. For a known resistors and capacitor, the frequency can be determined by a formula. From the math logic, if the frequency and the resistors are known, then an unknown capacitor could be determined by the inverse of the formula. Anyone who has a frequency counter are [...]

Current handling capability of a power supply system often needed to be checked. Finding high power rated variable resistor to provide variable load testing might be difficult. There is wire wound type but it’s not always available at your local store, and the price and performance might be disappointing. This variable high power “resistor” uses [...]

A PLL system can be used to build a frequency-selective frequency multiplier by inserting a frequency divider inside the feedback path between the VCO output and the phase error detector input. Here is the schematic diagram of a low-frequency synthesizer with a programmable three decades divider circuit. The frequency-divider modulus N can vary [...]

The first thing you must have in your workshop/lab is power supply. In experimenting many new electronic circuit design, it is easier if you have a flexible adjustable power supply. Here is an adjustable 0-30 volts power supply design. The circuit schematic diagram is shown below. The core of the circuit is 723 [...]