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Picture of Frequency Counter DIY 1Hz to 50MHz
Electronics is my hobby. I have home lab for my hobby, where I like to solder projects and discover circuits.

I found free posted circuit of Frequency Counter for DIY from russian developer. It can measure frequency up to 50MHz and the circuit is based on PIC16F628A microconroller and HD44780 LCD display. The original source you can visit here

I decided to take +5V from PC USB to abandon 7805 regulator. It allow me to have a nice USB device, which do not need battery or additional power supply.
Press to see my final circuit for frequency counter

Technical Specifications:
  • Auto Range Measure,  1Hz to 50MHz
  • Measurement cycle 1 second
  • Accuracy about 1%
  • Input Sensitivity 100mV AC peak
  • Device Size's: 85x40x35 mm
I designed double layer PCB for this project  with the dimensions almost like 16x2 LCD board, so I got very compact counter and it  can be installed to front panel of the enclosure. The LCD can be easily connected and disconnected any time if you need to access the components. I like to use oscilloscope probe for measurement, so I installed BNC Female Panel Connector to my enclosure and connected the BNC Jack with short coaxial cable to the PCB.

Components I used in this project:

1x Manufactured 2 Layers High Quality PCB 85x40 mm
1x LCD 16x2 HD44780 compatible
1x Trimmer Potentiometer top adjust 5K
2x 5% Carbon Film Resistor 47 Ohm
2x 5% Carbon Film Resistor 10K
1x 5% Carbon Film Resistor 220 Ohm
1x 5% Carbon Film Resistor 300 Ohm
1x Ceramic Disc Capacitor 10pF 50V
4x Ceramic Disc Capacitor 10nF 50V
1x Ceramic Disc Capacitor 100nF 50V
2x Multilayer Ceramic Capacitor 30pF 50V NP0
2x Electrolytic Capacitor 47uF 16V
1x Electrolytic Capacitor 100uF 10V
1x Electrolytic Capacitor 220uF 10V
1x SS9018 NPN RF Transistor
2x Silicone Diode 1N4148
1x 4.000Mhz Quartz Crystal HC49U
1x PIC16F628A Microcontroller flashed with hex
1x 18pin DIP Socket
1x USB type B Female PCB Connector
1x Male Pin Header 2 pins
1x Male Pin Header 16 pins for LCD connection
1x Female Pin Header Socket 16 pins for LCD connection
2x M2.5 x 6 Iron Bolts with Standoff

The final look of my Frequency Counter DIY Kit you can see on the pictures I attached. I also post the video with testing the counter. It do not need calibration, but if you have a precision function generator you can add variable capacitor and trim the quarts crystal frequency. I reserved place on the PCB for trimming capacitor.



The drawback of this project is long (1 second) Measurement cycle. It's mean that the readings on the display updated only every second. And if you want to use it with some Frequency Generator to control it frequency it may be uncomfortable when you scroll through the frequency's. 

But despite it, the DIY kit is very easy for assembling and soldering. It have English manual PDF with clear instruction for assembling steps and technical support by email.

You can purchase the full Frequency Counter DIY Kit on my webstore RadioHobbyStore


Thank you for reading!
Alexey