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
With major product releases coming from big names like Sony, Microsoft, and Samsung, and big investments by companies like Facebook, 2015 could be the year that virtual reality (VR) and augmented reality (AR) finally pop. Here's take a look back at some of the technologies that got us here (for better and worse).
Good engineering designs are those that work in the real world; bad designs are those that don’t. If we agree to set our egos aside and let the real world be our guide, we can resolve nearly any disagreement.
The Industrial Internet of Things is bringing a previously reluctant process industry into the wireless fold. The ability to connect smart sensors to the Internet has spiked the demand for wireless devices in process manufacturing, according to the new study from ARC Advisory Group.
If you’re developing an embedded monitoring and control application, then you’ll want to take note of the upcoming Design News Continuing Education Center class, “Embedded Development Using Microchip Microcontrollers and the CCS C Compiler."
US factory orders for durable goods tumbled 3.4% in December on a big drop in new bookings for commercial aircraft, according to data the Commerce Department released Tuesday.
More:Blogs|News
Design News Webinar Series
12/11/2014 8:00 a.m. California / 11:00 a.m. New York
12/10/2014 8:00 a.m. California / 11:00 a.m. New York
11/19/2014 11:00 a.m. California / 2:00 p.m. New York
2/25/2015 11:00 a.m. California / 2:00 p.m. New York
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Jan 26 - 30, IPv6 for Micros – Hands-On
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  67


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.
Last Archived Class
Sponsored by Stratasys
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2015 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service