Free Circuit Diagram

This is 10.7-MHz IF amplifier circuit. This circuit is used in many application such as cell phone base station receivers (final IF) and FM broadcast receivers. The ceramic filter that is used in this circuit are cheap and available in a variety of insertion losses and banwidths. This circuit uses a 230-kHz bandwidth filter SFELA10M7GA00-B0 [...]

pH Meter Circuit pH meter measures the voltage (the EMF, electromotive force) generated by the pH electrodes (the sensor) to show the hydrogen concentration in pH scale. Basically, a pH meter is nothing more than a pH probe/sensor with high impedance voltmeter that measures the generated voltage at the pH probe. To measure the [...]

This constant current constant voltage  SMPS can be used to efficiently charge a battery. This circuit gives 7.2V at constant voltage mode, and 600 mA at constant current mode. Here is the schematic diagram of the circuit: The mechanism is simple, when the load impedance is high, then the output voltage will be [...]

Voltage-Current curve tracer is very important tools for components ant circuits troubleshooting. This circuit need an oscilloscope with X-Y inputs to display the curve. This circuit provide adjustment for both peak-to-peak voltage and the current limiter. The peak-to-peak voltage selected using different voltage taps of the transformer, and the current limiter is selected by different [...]

For you who has failed to build  radio transmitters, this circuit worth a try. This circuit uses 74HC14 hex Schmidt trigger as the oscillator, and you can choose to use capacitor for low cost goal or quartz  crystal for better stability. For quartz crystal, you can choose any frequency between 00.7-1.6MHz, but around 1.6MHz is [...]

This is an application that can be used to adjust LED brightness while maintaining superior color quality. This application uses pulse width modulation (PWM) dimming technique. This application can be used for single-line scrolling displays, transportation road signs, simple scoreboards, ever-expanding advertising markets encompassing convenience gas stations, shops, stadiums, and stores. Following figures shows color [...]