Many electronic circuits requiring precision control of time use crystal oscillators. A simple crystal oscillator using only one NAND gate based CMOS 4011 shown in picture below. Resistor R1 biases the gate into a linear region and voltage division by capacitors C2 and C3 make a Colpitt’s oscillator.
A small trimmer in series with the crystal sets the frequency to it’s precise value. The circuit works well with crystals of up to 1 MHz. Owing to the inherent frequency limitations of the CMOS IC’s, the circuit will not work with RF crystals of 5 MHz or more. The output of the circuit can be connect to other RF amplifier.