This frequency counter may seem simple but it is capable of measuring frequencies in range between 10Hz – 60MHz with 10Hz resolution. Frequency counter circuit is based on PIC16F282A microcontroller clocked by 4MHz crystal.
Frequency counter has a transistor based TTL level converter where small signal is increased to level acceptable to PIC microcontroller logics. So it is capable of measuring signals from crystal oscillators. There is also no problem to use additional pre-scaller circuit and rise frequency range even to GHz level. I bet this frequency counter would find a place on any hobbyists workbench.