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
When you think of the DARPA Robotics Challenge, you may imagine complex humanoid contraptions made of metal and wires that move like a Terminator Series T-90. But what actually happened at the much-vaunted event was something just a bit different.
The machine is claimed to be the largest and most powerful electric pipe-bender on the market, exerting nearly 500,000 lb-ft of torque.
Traditional dev kits are based on a manufacturer’s microcontroller, radio module, or sensor device. The idea is to aid the design engineer in developing his or her own IoT prototype as quickly as possible. A not-so-traditional IoT development kit released by Bosch aims to simplify IoT prototyping even further.
This consulting firm has put together a report detailing the growing biomimicry design field in the US and around the world, from naturally bacteria-repelling surfaces to keratin-inspired polymers.
Here's a list of engineering and tech jobs ranked by outlook, work environment, stress, and income.
More:Blogs|News
Design News Webinar Series
1/28/2016 11:00 a.m. California / 2:00 p.m. New York
12/8/2015 11:00 a.m. California / 2:00 p.m. New York
2/18/2016 11:00 AM PT | 2:00 PM ET
2/24/2016 11:00 AM PT | 2:00 PM ET
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Jan 11 - 15, Designing ARM Devices Using Segger Tools
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6 |  7 | 8 | 9


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

Sponsored Content

Technology Marketplace

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