Vermes
Advanced Member level 4
It is a design of very sensitive frequency meter on commonly used parts and components. Remember not to use a trimming capacitor with three terminals. In this project – the meter run after using two terminals. Transistor Q1 is BF256B. It needs to be rotated 180 degrees in comparison to what is on the original board. There is no need to design a housing, because holding the device in hands does not interrupt the measurements. It consumed 20mA at 9V supply from a battery.
The meter was taken from LINK. You can find there the load for the processor, PCB drawing and the whole description.
Pictures:
Link to original thread (useful attachment) – Miernik częstotliwości do 50MHz na LCD