This circuit was found in RCA documentation from the 1980s. The circuit uses LDRs of the time and the 50 uA instrument has zero in the center. R1 and R2 may have 2k2 and R3 10k typically.
This good gain antenna up to 30 MHz was found in an American 1990s documentation. The circuit can be...
This converter can be used to send information remotely from linear transducers, converting voltages...
This timer with 1 second accuracy was obtained in a 1973 documentation. The Buzzer is a low-power type...