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
Transfers the control of a large number of motion axes from one numerical control kernel to another within a CNC system, using multiple NCKs, and enables implement control schemes for virtually any type of machine tool.
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