We found this circuit in a 1966 US documentation. It simulates a variable capacitor that can vary capacitance from 1,000 to 1. Transistors are general purpose types.
This level matrix display was found in a 1994 documentation, but it can still be assembled, as the...
This receiver receives signals in the range of 3.2 to 16 MHz, presenting a good sensitivity thanks...
We have in the figure a traditional amplifier configuration with operational amplifier. The source...