We found this circuit in a 1964 Electronic Design. It divides the frequency of a 20 MHz signal by 2. The circuit uses a transistor from that time. Details of the coils were not given.
We found this circuit in a 1980s American documentation. The operational amplifiers of the...
This input circuit for an oscilloscope was found in Radio Electronics from the 90s. The operating...
This circuit emits a sound when a magnetic field, of a magnet, for example, approaches the sensor....