This circuit was found in an old Poptronics. Operational amplifiers can be replaced with equivalents. The power supply must be symmetrical.
This circuit can be used as a shield when its supply is 5 V. in this case we can exchange the...
This reflectometer or standing-wave ratio meter (SWR) was found in a 1980s American documentation. The...
This circuit is from Motorola's 1990 Linear Databook. The integrated circuit used is no longer...