HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
Comment
Jon Titus
User Rank
Blogger
Re: Part IV: Fundamentals of Digital Debugging
Jon Titus   1/19/2012 3:19:31 PM
NO RATINGS
Q: Re: power problems with logic circuits. I designed a CMOS (not MCU) circuit for a starlight camera control function, and while it worked perfectly on the bench, it didn't work when hooked up the the camera system. It took a memory storage scope to discover that the pan/tilt function, which was 120 VAC switched by electromechanical relays, was generating extreme voltage spikes that showed up in the logic as spurious signals. Fixing the problem required capacitor filters across every 120 V relay contact.


So if it works in the lab, but not the actual environment, start looking beyond the MCU.

 

A:  Yup.  But in the lab you might have found the problem if you simulated the tilt/pan loads and ran 110V to them.  Switching loads with relays almost always causes problems, either from RFI caused by the contact closure or by back EMF caused when the relay coil field "collapses."  To reduce contact switching, look for a solid-state relay with zero-crossing switching.  That arrangement will limit inrush current as the 110V AC line voltage is at zero when the SSR switches.




Partner Zone
Latest Analysis
For decades there have been rumors that Microsoft essentially copied DRI's CP/M operating system and sold it to IBM as MS-DOS. In just a few days, all will be revealed.
A San Francisco startup called Otto came out of stealth mode recently and released a dramatic video demonstrating its successful test of a technology for self-driving trucks.
Researchers have found a way to use graphene to cheaply and easily turn dirty water into drinking water.
A new 1-GHz vector signal transceiver promises to offer expanded test capabilities for engineers involved in applications ranging from automotive and aerospace to semiconductors and defense.
Researchers at the Masdar Institute of Science and Technology have devised a new method for designing strong, light cellular structures of re-architected metals and plastics with optimized properties.
More:Blogs|News
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6 |  7 | 8 | 9 | 10


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.
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Technology Marketplace

Copyright © 2016 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service