Suggested by General Electric in a 1968 documentation this integrated amplifier uses a component of the era, the PA237. The circuit runs on 24 V and excites a 16-ohm speaker.
ON Semiconductor CMOS Operational Amplifiers Mouser Electronics announces the availability of ON...
An OR gate can be improvised using NAND gates of a 4001 as shown here. The diodes are...
This circuit was found in a 1991 publication. The transistor can be a general-purpose type....