This is simple Colpitts oscillator to test commonly available passive crystals which range between 2MHz to 27MHz. This unit must connect to an oscilloscope and/or frequency counter to get the frequency of the crystal.

This circuit is design to work around 9V to 12V DC power source. Both 2SC930 transistors can replace with any high speed NPN transistor such as 2SC829, 2SC933, etc.

In our lab we use Manhattan style layout to prototype this crystal tester and it produces highly accurate results with above specified frequency range.
According to our observations, after 27MHz, amplitude of the waveform starts to decrease steeply.

Stripboard wiring layout for this crystal tester.

Project Related Downloads

Schematic and Stripboard - wiring layout for simple crystal tester unit.


2SC930 - NPN Silicon Epitaxial Planar Transistor