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 [...]

The transmitters that either working in FM or in AM is familiar. This is transmitters circuit that can transmit both FM and AM signal simultaneously at two different frequencies FM in 100Mhz and Am in 20 MHz. Here is the circuit: To transmit the FM signal, this circuit uses the 5th harmonics [...]

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 [...]

I some cases, a differential input is needed for voltage measurement. Using the only one operational amplifier, you can build an adapter to provide a floating input for your ground-referenced  voltmeter. Use 1% tolerance metal film resistor for R1 and R2.  Adjust VR1 to give zero voltage output when the input probe is [...]

Autoranging is useful to extend the measurement range of an available ADC (analog-to-digital converter).  Autoranging will best implemented for multiplexed input.  LTC1257 is appropriate for system autoranging, adjusting an ADC’s full-scale range. During the conversion process, U2 and U3 receive the full and zero scale codes, respectively, that correspond to a [...]