the short version
The Complete Story
Greb and Adams
Herrold Dot Org

Read Mike Cassidy's Story in the Mercury News | Watch the Complete Herrold Documentary

Below, a recreation of a Herrold broadcast from the PBS documentary "Broadcasting's Forgotten Father: The Charles Herrold Story"

Below is an overly simplistic view of a Herrold broadcast as it might have happened in 1912


In radio broadcasting, sound in the form of voice and music, is transmitted from a studio to your home or car radio. Every modern radio works about the same way regardless if it's a cheap low model brand or even more expensive ones you might get through an equipment lease. This is the Herrold "on air studio," all analogue, circa 1913:

1. Grooves on spinning record vibrate needle & diaphragm
2. Audio is concentrated using small funnel replacing large horn
3. Audio, music & voice, is picked up by a carbon microphone

All About this Device
Above is a 1907 schematic drawing of an arc transmitter made by Lee de Forest. In the Herrold transmitting device a direct current arc (1) was coupled to an antenna coil (3), and the coil was connected to the microphone (2) and then to a ground. Danish inventor Valdemar Poulson discovered this means of transmitting audio, but it quickly became obsolete after the first de Forest vacuum tube transmitter appeared in 1916.

The most famous Herrold photograph and accompanying press

The final element needed for broadcasting is the audience. During the time of the Herrold broadcasts, 1909 - 1917, most radio transmission was Morse code, a single sender and a single known receiver. Herrold's audience were mostly young experimenters and set builders, their friends and parents, and students of the Herrold College. In the days before modern electronics they listened on headphones connected to crystal detector and coil, antenna and ground.

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