element14 Community
element14 Community
    Register Log In
  • Site
  • Search
  • Log In Register
  • About Us
  • Community Hub
    Community Hub
    • What's New on element14
    • Feedback and Support
    • Benefits of Membership
    • Personal Blogs
    • Members Area
    • Achievement Levels
  • Learn
    Learn
    • Ask an Expert
    • eBooks
    • element14 presents
    • Learning Center
    • Tech Spotlight
    • STEM Academy
    • Webinars, Training and Events
    • Learning Groups
  • Technologies
    Technologies
    • 3D Printing
    • FPGA
    • Industrial Automation
    • Internet of Things
    • Power & Energy
    • Sensors
    • Technology Groups
  • Challenges & Projects
    Challenges & Projects
    • Design Challenges
    • element14 presents Projects
    • Project14
    • Arduino Projects
    • Raspberry Pi Projects
    • Project Groups
  • Products
    Products
    • Arduino
    • Avnet Boards Community
    • Dev Tools
    • Manufacturers
    • Multicomp Pro
    • Product Groups
    • Raspberry Pi
    • RoadTests & Reviews
  • Store
    Store
    • Visit Your Store
    • Choose another store...
      • Europe
      •  Austria (German)
      •  Belgium (Dutch, French)
      •  Bulgaria (Bulgarian)
      •  Czech Republic (Czech)
      •  Denmark (Danish)
      •  Estonia (Estonian)
      •  Finland (Finnish)
      •  France (French)
      •  Germany (German)
      •  Hungary (Hungarian)
      •  Ireland
      •  Israel
      •  Italy (Italian)
      •  Latvia (Latvian)
      •  
      •  Lithuania (Lithuanian)
      •  Netherlands (Dutch)
      •  Norway (Norwegian)
      •  Poland (Polish)
      •  Portugal (Portuguese)
      •  Romania (Romanian)
      •  Russia (Russian)
      •  Slovakia (Slovak)
      •  Slovenia (Slovenian)
      •  Spain (Spanish)
      •  Sweden (Swedish)
      •  Switzerland(German, French)
      •  Turkey (Turkish)
      •  United Kingdom
      • Asia Pacific
      •  Australia
      •  China
      •  Hong Kong
      •  India
      •  Korea (Korean)
      •  Malaysia
      •  New Zealand
      •  Philippines
      •  Singapore
      •  Taiwan
      •  Thailand (Thai)
      • Americas
      •  Brazil (Portuguese)
      •  Canada
      •  Mexico (Spanish)
      •  United States
      Can't find the country/region you're looking for? Visit our export site or find a local distributor.
  • Translate
  • Profile
  • Settings
Passive Components
  • Technologies
  • More
Passive Components
Forum Dealing with Unexpected Emissions: The Fellowship of the Ferrite Ring
  • Blog
  • Forum
  • Documents
  • Quiz
  • Events
  • Polls
  • Members
  • Mentions
  • Sub-Groups
  • Tags
  • More
  • Cancel
  • New
Join Passive Components to participate - click to join for free!
Actions
  • Share
  • More
  • Cancel
Forum Thread Details
  • Replies 21 replies
  • Subscribers 106 subscribers
  • Views 4355 views
  • Users 0 members are here
  • ferrite ring
  • MXO4
  • emc
  • MXO 4
  • spectrum analyzer
  • toroid
  • choke
  • oscillator
  • ferrite core
  • Fair-Rite
  • ferrite
  • inductor
Related

Dealing with Unexpected Emissions: The Fellowship of the Ferrite Ring

shabaz
shabaz over 2 years ago


I was experimenting with bits of circuit, hopefully, to become a power supply eventually. It is a work in progress.

At this stage, I’m using bits of scrap copper-clad board, each with a sub-module. It’s too early for a PCB.

image

However, during the prototyping, I noticed (amongst other issues that I need to solve!) a particular artifact on the ‘scope trace when looking at the output.

This situation ended up being a good example of where it pays to zoom out and look at a lot more of the spectrum view than expected!

Admittedly this was a lot easier to identify using the MXO 4 ‘scope, but it would be possible to spot with other test equipment, such as a spectrum analyzer and a near-field probe. I just used the normal 'scope probe, I didn't do anything special.

With the MXO 4, the anomaly was zoomed in, and then using a logarithmic-frequency spectrum view, it was possible to see the extent of the problem, with the left side of the spectrum view showing the wanted oscillation (fundamental frequency) and its harmonics, and the right side showing the spurious output.

image

Now I could try to do something about it!

I used tiny ferrite rings (legend has it they were forged by Fair-Rite, part code 2643001501 ) on the base input of the transistors. Essentially, they act as a bit of additional resistance for the higher frequencies. The rings cost $0.02 currently (although more expensive in the UK).

image


Back to the ‘scope:

image

Much better!

As mentioned, I still have other problems to deal with, but I thought it was a nice example of why it makes sense to do testing to frequencies far higher than expected, just in case there are spurious emissions, and why it can be a good idea to possess the rings because one never knows when they are needed.

Thanks for reading!

  • Sign in to reply
  • Cancel

Top Replies

  • Jan Cumps
    Jan Cumps over 2 years ago in reply to anniel747 +3
    or nail polish. Also good to fix broken-off enamel.
  • robogary
    robogary over 2 years ago +2
    nice. I wouldnt have looked that closely to notice the ring.
  • anniel747
    anniel747 over 2 years ago in reply to shabaz +2
    Or conventional varnish dip.
Parents
  • wolfgangfriedrich
    wolfgangfriedrich over 2 years ago

    I am sure the company is called Fairy-Rite, because their parts do some real magic.

    • Cancel
    • Vote Up +1 Vote Down
    • Sign in to reply
    • Cancel
  • shabaz
    shabaz over 2 years ago in reply to wolfgangfriedrich

    Yes! : ) They should write a book, "Fairy-Rite Tales that Came True", about how circuit problems were solved.

    Sold with a bunch of ferrites on golden thread : )

    • Cancel
    • Vote Up 0 Vote Down
    • Sign in to reply
    • Cancel
Reply
  • shabaz
    shabaz over 2 years ago in reply to wolfgangfriedrich

    Yes! : ) They should write a book, "Fairy-Rite Tales that Came True", about how circuit problems were solved.

    Sold with a bunch of ferrites on golden thread : )

    • Cancel
    • Vote Up 0 Vote Down
    • Sign in to reply
    • Cancel
Children
No Data
element14 Community

element14 is the first online community specifically for engineers. Connect with your peers and get expert answers to your questions.

  • Members
  • Learn
  • Technologies
  • Challenges & Projects
  • Products
  • Store
  • About Us
  • Feedback & Support
  • FAQs
  • Terms of Use
  • Privacy Policy
  • Legal and Copyright Notices
  • Sitemap
  • Cookies

An Avnet Company © 2025 Premier Farnell Limited. All Rights Reserved.

Premier Farnell Ltd, registered in England and Wales (no 00876412), registered office: Farnell House, Forge Lane, Leeds LS12 2NE.

ICP 备案号 10220084.

Follow element14

  • X
  • Facebook
  • linkedin
  • YouTube