LEAP#207 Frequency Counter

Testing a CMOS frequency counter circuit with a 100Hz - 5MHz range.

I found this circuit published in Electronics magazine (Sep 16 1976). It's a classic demonstration of the CD4026 "bucket-brigade" and CD4047 astable oscillator.

The frequency counter is governed by a CD4047 oscillator. Since this offers a clean 50% duty cycle, it is ideal for flipping the circuit between two modes: sampling period; display period.

As always, all notes, schematics and code are in the Little Electronics & Arduino Projects repo on GitHub.