sensing pin

The punch unit had sensing pins in place of the punches.

At the next station sensing pins read the holes present in the original card and transferred the data to the punching station and onto a blank card.

In design, it differed radically from the earlier 056 verifier, in that it used optical sensing of card holes instead of mechanical sensing pins.

However, the mechanical tape readers used in most standard-speed equipment had no problem with chadless tape, because it sensed the holes by means of blunt spring-loaded sensing pins, which easily pushed the paper flaps out of the way.

The first use in this sense is in the files of Merriam-Webster: "The small discs, called chads," noted the RCA Review in 1947, ". . . are perforated only sufficiently to permit the chads to rise like small hinged lids in response to the sensing pins of a transmitter."