John Beigel, a consultant for MEDER electronic, a manufacturer of reed relays, took exception to my reed-relay bounce-time data, obtained from a Keithley Instruments handbook, and responded, "The vast majority of reed relays are single pole single throw (SPST) normally open contacts. The majority of the contacts close completely in approximately 0.5 milliseconds. This includes bounce. Bounce typically lasts about 100 to 150 microseconds. On new reed relays the operate time is typically 100 microseconds max with a bounce time of 50 microseconds maximum. The bounce time called out by Mr. Titus--'a few milliseconds'--is simply not true."
I obtained sample relays from MEDER and measured relay-bounce times of about 50 microseconds. But other electro-mechanical characteristics as well as test-and-measurement applications also govern the use of relays. Read my follow up column set for the August 2011 issue of Design News. --Jon Titus
Fifty-six-year-old Pasquale Russo has been doing metalwork for more than 30 years in a tiny southern Italy village. Many craftsmen like him brought with them fabrication skills when they came from the Old World to America.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.