RF Cafe Software
About RF Cafe
1996 - 2022
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.
My Hobby Website:
Try Using SEARCH
to Find What You Need.
There are 1,000s of Pages Indexed on RF Cafe !
August 1955 Popular ElectronicsTable of Contents
People old and young enjoy waxing nostalgic about and learning some of the history of early electronics. Popular Electronics was published from October 1954 through April 1985. All copyrights are hereby acknowledged. See all articles from Popular Electronics.
The Underwriter's Laboratory (UL) is an entity that seems to have been around forever. A lot of people - maybe most people - assume that it is a government entity. In fact, it is a non-profit organization sponsored by the National Board of Fire Underwriters. Its roots are traceable back to the Chicago World's Fair in 1893. Concern over the potential fire hazard of Edison's light bulbs was the impetus for the effort. Another aspect of the UL that a lot of people don't know is that the UL label of approval is no guarantee that the device works properly, only that is passes standards of safety as it relates to fire hazards. This article in the August 1955 edition of Popular Electronics gives a brief history.
Behind the U.L. Label
By E. D. MORGAN
Equipment is tested, dropped, pounded, and
burned before it is rated as safe and tagged
with the Underwriters' okay.
A familiar sight on much electrical and electronic equipment used today is an Underwriters' Laboratories
label. Exactly what is implied by the use of this label, however, is often misunderstood.
Underwriters' Laboratories, Inc. is a non-profit organization sponsored by the National Board of Fire Underwriters. Its function is to test and inspect materials and equipment to prevent loss of life and property from fire, crime and casualty hazards. To do this adequately, it subjects devices to grueling tests. Only the hardiest designs survive and earn the right to the coveted label of acceptance.
No conceivable method of testing is overlooked. Much of the test equipment is of U. L.'s own design and they dream up diabolical plans to subject samples to the meanest treatment possible. They try to anticipate all of the mistakes that could be made by a consumer. Appliances are left on for weeks and electric heater cords are twisted and untwisted thousands of times.
Television cabinets get a thorough pounding before they receive U. L. approval. A large picture tube can be a deadly weapon when broken, as it hurls tiny fragments of glass in all directions. To insure against injury, the safety screen on the front must be capable of withstanding such shattering. A pound-and-aquarter steel ball is hurled at the set to determine its fitness for this purpose.
Electronic equipment is often used by U.L. technicians. Here, the split-second operation of a burglary detection system is photographed. Accuracy is assured by using a cathode-ray oscilloscope, a beatfrequency generator, and various meters.
To determine whether a safe is fireproof and burglar-proof, U. L. employs its own staff of "arsonists" and "safecrackers." These men are masters at their trades and tackle a new item with drills, sledges, torches, and explosives. Just to make sure, the safes are dropped onto concrete from a second-story level, then placed in a 2000° F furnace for an hour or so. If the internal temperature goes high enough to turn valuable papers brown, what is left of the safe is returned to the maker with regrets.
Good will and impeccable honesty is the main stock-in-trade of this organization. U. L. never solicits business, but industry has learned that it is well worth the effort to make sure its products deserve the U. L. label.
Posted August 26, 2011