Stone Vintage Radio Museum - Antique Radios, Wireless, Crystal Sets, Tubes, and Valves

Coherers predate tubes, magnetic detectors, and crystals as detectors. Their use even predates radio. It was the first detector used for radio reception. In the glass tube there is a very small opening between the two metal plugs; in that opening there are metal filings. When a radio signal is received, the filing clump together. The door bell (minus the bell) was used to knock the filings apart after they cohered when a radio signal was received. Here is an experimentor's coherer mounted on a telegraph sounder's base. The patent date on the coil is 1894. I assume this one is from the teens or 20s.

Unless otherwise noted, all materials contained on this web site are copyright protected. Materials may be downloaded and/or reprinted for personal use only. Permission to reprint or electronically reproduce any document or graphic in whole or in part for any non-personal or commercial use is expressly prohibited unless prior written consent is obtained from the respective copyright holder(s).