Free Circuit Diagram

This radio modem is popular for amateur radio packet application. This radio modem is powered by the data and control lines, so it need no additional power supply. Just plug to your standard RS232 port and this modem will work. As seen in our previous modem circuit, this radio modem circuit also uses TCM3105 modem [...]

TDA 1072AT is a special purpose integrated circuit for AM radio receiver from Philips Semiconductors. The integrated circuit is designed for mains-fed home receivers and car radios. The voltage-controlled oscillator provides signals with extremely low distortion and high spectral purity over the whole frequency range even when tuning with variable capacitance diodes. RF radiation and [...]

This video tutorial  is about servo motor that controlled by PWM signal.  There should be two electrical input, one for the power and  another for the control signal (to command a position). This servo motor is very common that can be found in the radio control cars and airplanes. The position of  the servo motor [...]

A phase control circuit can be used to control the power delivered to an AC load. The phase control circuit control the AC waveform, cutting the cycle to give full cycle, half cycle, zero cycle, or somewhere in between. You can say this circuit is similar to a dimmer circuit, but the switching is synchronized [...]

Speed control for dc motor (electric motor) can be implemented using open loop or closed loop. Closed loop controller, also known as servo controller,  or a feedback control, gives the best performance since the loop will maintain the actual speed to follow the reference. In simple application, an open loop controller can be enough if [...]

LM56 is a monolithic  thermostat designed for simple temperature control. The chip has two programmable threshold that can be used to drive a fan and or alarm.  Here is the schematic diagram of the fan control circuit: /caption] The circuit will turn on the fan when the temperature rise above 50 [...]