This high-speed circuit was found in 1980s Linear Technology documentation. The circuit makes use of components of the time with TTL output and TTL input that enable their use as a shield.
July 2017 - Mouser Electronics has in its stock the new infrared (IR) emitters from OSRAM Opto...
This circuit is from a 1966 NASA documentation. The circuit uses a photodiode as a sensor. The other...
This doorbell or buzzer as announced in a 1990s US publication uses an operational amplifier that admits...