Discover the origins of the headphone jack in 19th-century telecommunications, tracing its unexpected journey from switchboards to soundboards. This episode reveals how a simple, spring-loaded connector became the backbone of audio and communication tech for over a century. 

Scribner, C. (1884, February 5). TELEPHONE SWITCH. 

Oskay, W., Schlaepfer, E. (2022). Open Circuits. No Starch Press.

Springer. Chapuis, R. J., & Joel, A. E. (2003). 100 years of telephone switching (1878-1978). IOS Press : Ohmsha.