Free Circuit Diagram

If you need +-15 Volts supply and you have only a standard 12V AC transformer, don’t be hurry to buy a new one with center tap, you can use your old transformer! The schematic diagram of this circuit is shown in the figure below. The voltage before entering the regulator IC [...]

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 [...]

This switch mode step-down converter has very good efficiency, up to 94% can be obtained. This switch mode regulator uses LTC1266-3.3 controller with external N-Channel power mosfet, and need only a 5uH inductor because it uses high frequency switching. Here is the schematic diagram of this switch mode step down converter circuit: To [...]

Using VFC110 chip, we can build a high frequency voltage-to-frequency converter. The features of this chip include the capability of high frequency operation, disable function, and an on-board precision 5V reference. This precision reference can be used to provide reference for offsetting the VFC transfer function, as well as provide transducer or bridge excitation. As [...]

This class-D audio power amplifier is suitable for TV and home stereo set. TDA7882 IC chip provides class-D audio power amplifier solution. Since this chip has only mono channel, you need two pieces of this circuit for stereo application. The power supply voltage is flexible, accept (+-)10V to (+-)25V. This circuit needs a split supply [...]

In some PLL application, sometimes we need to provide lock indication when the PLL is in locked state. The simplest one is binary indication, 0 or 1 to correspond with lock/unlock condition. This  condition should be easy to be presented with a LED lamp. The schematic diagram  shows a lock-detection scheme [...]