We found this frequency meter circuit in a 1974 documentation. The circuit is powered by 12 V and has 8 digits. Changes can be made using a prescaler to reach higher frequencies.
This intercom uses transistors from the 60s. It was found in a Japanese publication at the time....
A The adjustable Q-factor rejector filter in the figure is based on two LM110. These integrated...
Found in Electronics Now this circuit can generate signals up to a few tens of Megahertz. The circuit...