This filter for the 300 Hz to 3 kHz range was found in an American documentation from the 90's. The operational amplifier is a double 741.
This circuit was obtained from an English magazine from 1976. The circuit operates two LEDs and...
Found in a publication from the 60's, this power supply has no regulation, but only current...
This circuit can use the LM148 and its more modern equivalents, generating a sinusoidal signal whose...