Electronics World articles Popular Electronics articles QST articles Radio & TV News articles Radio-Craft articles Radio-Electronics articles Short Wave Craft articles Wireless World articles Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors LinkedIn Crosswords Engineering Humor Kirt's Cogitations RF Engineering Quizzes Notable Quotes Calculators Education Engineering Magazine Articles Engineering software RF Cafe Archives Magazine Sponsor RF Cafe Sponsor Links Saturday Evening Post NEETS EW Radar Handbook Microwave Museum About RF Cafe Aegis Power Systems Alliance Test Equipment Centric RF Empower RF ISOTEC Reactel RF Connector Technology San Francisco Circuits Anritsu Amplifier Solutions Anatech Electronics Axiom Test Equipment Conduct RF Copper Mountain Technologies Exodus Advanced Communications Innovative Power Products KR Filters LadyBug Technologies Rigol TotalTemp Technologies Werbel Microwave Windfreak Technologies Wireless Telecom Group Withwave RF Cafe Software Resources Vintage Magazines RF Cafe Software WhoIs entry for RF Cafe.com Thank you for visiting RF Cafe!
ConductRF Phased Matched RF Cables - RF Cafe

TotalTemp Technologies (Thermal Platforms) - RF Cafe

Amplifier Solutions Corporation (ASC) - RF Cafe

Please Support RF Cafe by purchasing my  ridiculously low-priced products, all of which I created.

RF Cascade Workbook for Excel

RF & Electronics Symbols for Visio

RF & Electronics Symbols for Office

RF & Electronics Stencils for Visio

RF Workbench

T-Shirts, Mugs, Cups, Ball Caps, Mouse Pads

These Are Available for Free

Espresso Engineering Workbook™

Smith Chart™ for Excel

LadyBug LB5954L Power Sensor with LAN Option - RF Cafe

Bell Telephone Laboratories - Ethylene Diamine Tartrate Crystals
October 1947 Radio-Craft

October 1947 Radio-Craft

October 1947 Radio Craft Cover - RF Cafe[Table of Contents]

Wax nostalgic about and learn from the history of early electronics. See articles from Radio-Craft, published 1929 - 1953. All copyrights are hereby acknowledged.

Occasionally when I post a Bell Telephone Laboratories (aka Bell Labs) promotion from a vintage electronics magazine, someone writes to challenge the claim being made by Bell Labs of having been the progenitor of the idea. This full-page ad apparently claiming to have developed the process needed to grow high purity crystals appeared in a 1947 issue of Radio-Craft magazine. The huge EDT (Ethylene Diamine Tartrate) crystal shown was created over a three-month period. Its intended use was for filters in telephone communications circuits. Development of the crystal growing process is yet another case of "necessity being the mother of invention," given that the massive increase in demand for phone service across the country left the company short on filter crystals. Bell Telephone Laboratories' manufacturing arm, Western Electric, assumed the responsibility of crystal production as part of their telephone handset and switching stations component effort.

Bell Telephone Laboratories EDT Crystals

Bell Telephone Laboratories, October 1947 Radio-Craft - RF CafeA Crystal that grew from a seed ... The large crystal in the foreground is an EDT (Ethylene Diamine Tartrate) crystal. It started from a seed (a piece of mother crystal) and in three months grew in a slowly cooling solution to the size shown. The small plate is cut from a large crystal, then gold-plated for electrical connection and mounted in vacuum. Cultivated EDT crystals can do the same job as quartz in separating the nearly 500 conversations carried by a coaxial circuit.

Crystals for Conversations

At war's end, the Bell System began to build many more Long Distance coaxial circuits. Hundreds of telephone calls can be carried by each of these because of electric wave filters, which guide each conversation along its assigned frequency channel. Key to these filters was their frequency-sensitive plates of quartz.

But there was not enough suitable quartz available to build all the filters needed. Bell Telephone Laboratories scientists met the emergency with cultivated crystals. Years of research enabled them to write the prescription at once - a crystal which is grown in a laboratory, and which replaces quartz in these channel filters.

Now Western Electric, manufacturing unit of the Bell System, is growing crystals by the thousands. Many more Long Distance telephone circuits, in urgent demand, can be built, because the scientists of Bell Telephone Laboratories had studied the physics and chemistry of artificial crystals.

Bell Telephone Laboratories

Exploring and Inventing, Devising and Perfecting, for Continued Improvements and Economies in Telephone Service



Posted December 4, 2020

Bell Telephone Laboratories Infomercials
LadyBug LB5954L Power Sensor with LAN Option - RF Cafe
Innovative Power Products Passive RF Products - RF Cafe

RF Cascade Workbook 2018 by RF Cafe

RF Electronics Shapes, Stencils for Office, Visio by RF Cafe