This is a simple frequency counter based on a micro-controller PIC16F84. Its maximum working frequency is around 30MHz, and have a 10Hz resolution, and having low current consumption (15mA), and very simple assembly. This uses 7 numbers seven segment LED display to display the frequency. The electrical schematic is very simple, given that most of
the functions are implemented by microprocessor. Here is another version of this counter, using LCD displays and having many more features. Check Digital frequency counter to get the circuit of a VHF pre-scalar.