Dilshan Jayakody writes:
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.
More details at Dilshan Jayakody’s blog.