Ground loop elimination in video systems does not always ask for a complete isolation of the grounds. There are passive hum suppressor transformers that will very effectively remove the hum from the video signal, but do not affect the video signal otherwise. Those special transformers act like a common mode coils, which stop the annoying ground loop currents on the shield of the coaxial cable, but provide a straight path for the signal inside the cable. This type of device is capable of passing the signals from DC to tens of MHz without problems. The hum suppressor transformer both reduces the current flowing on the cable shield and compensated the voltage differences that would otherwise be between cable ends and eventually get to the signal.
The humbugging transformer/coil consists just of many (tens to hundreds) turns of 75-ohm miniature video coaxial cable wind on a suitable transformer core. The aim is to have a coil that has high enough inductance to keep the cable shield current low and still withstand the voltages/currents it gets exposed to in typical applications without saturation. This kind of hum reduction coil works by mutual inductance. The coax cable is wound around a transformer core so that both the inner and shield of the cable become inductors. The tight coupling ensures that any voltages/currents flowing on the cable shield, caused by variations in earth potential differences, are transformed into the inner conductor. This type of transformer is typically constructed to a specially selected toroid transformer core.
This type of hum suppression transformer has found it’s way to the professional video application (rental companies) and computer video applications (computer to video projector connections). The transformers of this type are usually called “hum bug transformers”, “hum-bucking transformers”, “anti-hum video transformers”, “hum suppressor transformers” or “video isolation chokes”. T The humbugging transformer presents a simple transmission line to the signal, so that its signal amplitude capability is essentially unlimited, and its bandwidth extends from DC to that frequency where line losses become excessive. Isolation increases with increasing noise frequency. The choke provides protection against moderate levels of 60 Hz hum, and protection against very high levels of RF noise. ypical performance figures are 30-40 dB hum level reduction up to 2-10V volt voltage differences at mains voltage frequency (50 Hz or 60 Hz). The maximum voltage the humbugging transformer can handle at low frequencies depends on the transformer specifications, usually limited by transformer core saturation. The humbugging transformer choke is primarily used in Broadcast TV because it passes the DC component of the signal. It is used in studio, and in remote ENG.
This picture shows the inside a commercially sold “video hum bug transformer” sold by Finnish company RGB. The price range of this kind of commercial device is usually 100-200 US dollars range. I had to open this unit to change the BNC connector that was broken on a field use. This device consists of a toroid shape transformer core and around 50 turns of very thin 75-ohm video coaxial cable wrapped around it. You can make your own working similar device by taking he core from a 100-400W toroidal mains power transformer and winding 30-50 turns of thin 75-ohm coaxial cable around it. This will work well but is somewhat larger and heavier than the commercial devices like this. It is possible to optimize the size with careful selection of suitable core material and number of turns.
Here is an inside views of some humbugging video transformer products that I have made. They have performed very well on many video systems to solve ground loop problems.
I love reading and I am always searching for informative information like this! You are bookmarked!. . . . . .
I agree with the author that we need to share the knowledge we gain!. . . . . .
Hi, there. This is a very extraordinary weblog and some great concepts as part of your submit. I’ll be back again. Gives thanks with the great content. By the way, why not listing your website in our E-Commerce directory and get a again link from us?
Our computer guy recommends wiping the hard drive clean once a year to keep it running fast. It’s a pain but really does keep our computers at top speed!
Hrmm that was weird, my comment got eaten. Anyway I wanted to say that it’s nice to know that someone else also mentioned this as I had trouble finding the same info elsewhere. This was the first place that told me the answer. Thanks.
Are you joking? I’m not certain I can support what you say. But I will certainly be back to check this out soon.
I am not joking.
Hey…thanks for that. Neat idea. I’ll be coming back tomorrow for more news. Excellent!
Useful post, but the sidebar don’t format properly on my Powerbook…perhaps you should take a look. Thanks, anyway.
very good article,thans for your sharing
Excellent post. I want to thank you for this informative read, I really appreciate sharing this great post. Keep up your work. .
Hi, I do not normally post feedback on web sites, as I prefer to read only. However I find the blog that you have created earlier has very insightful information, and I discover it very informational. I was searching on Google 4 how to set goals information & found your eye opening web site. Could you post something the same superb on how to set goals? Thanks. ~ Tamela Newman
Hi dude, can i post articles to your website ? Let me know if you are interested
What kind of articles you have in your mind?
Good relevant articles are always wellcome…
at first i thought its a yucky bug..
Your header is a bit wonky in Opera, mate.
It’s arduous to search out knowledgeable individuals on this topic, http://www.lanescarproducts.com but you sound like you know what you’re speaking about! Thanks
I appreciate your piece of work, thanks for all the informative blog posts.
Rattling instructive and excellent body structure of subject material , now that’s user genial (:.
I can’t remember a lot the way i got right here, but boy oh yea boy I really didn’t need to hesitate and read a few of your entries, they are all right works of publishing and incredibly much great opinions on just about this particular hard subject. Rock on my friend.
After research a few of the blog posts on your website now, and I really like your method of blogging. http://www.vipappliancerepair.com I bookmarked it to my bookmark web site checklist and might be checking again soon. Pls take a look at my web page as properly and let me know what you think.
After study a few of the blog posts on your website now, and I really like your way of blogging. http://www.allstatepools.com I bookmarked it to my bookmark web site checklist and will likely be checking back soon. Pls try my web page as nicely and let me know what you think.
I have been browsing online more than 3 hours today, yet I never found any interesting article like yours. It is pretty worth enough for me. In my view, if all web owners and bloggers made good content as you did, the net will be much more useful than ever before.
Have you ever considered creating an ebook or guest authoring on other blogs? I have a blog centered on the same subjects you discuss and would really like to have you share some stories/information. I know my subscribers would value your work. If you are even remotely interested, feel free to send me an e-mail.
very nice blog!
I’ve observed that in the world the present moment, video games are the latest trend with kids of all ages. Occasionally it may be extremely hard to drag the kids away from the video games. If you want the best of both worlds, there are plenty of educational games for kids. Thanks for your post.
Barking up the wrong tree.
Hello, i believe that i saw you visited my weblog thus i got here to ¡§go back the favor¡¨.I’m trying to find things to improve my site!I suppose its ok to make use of a few of your concepts!!
[...] on them and links to video isolator products. For DIY solutions read my Build video isolator and Build humbugging transformer blog [...]
Thanks for the good writeup. It in fact used to be a enjoyment account it. Glance complicated to far brought agreeable from you! By the way, how can we communicate?
Woah! I’m really digging the template/theme of this website. It’s simple, yet effective. A lot of times it’s challenging to get that “perfect balance” between superb usability and visual appeal. I must say you’ve done a very good job with this. Additionally, the blog loads super fast for me on Safari. Exceptional Blog!
I personally liked studying it. I have to discover much more about this subject. I’m admiring time and effort you put in your site, because its perfect location where I can discover lot of useful articles.
Thank you for your feedback on my article.
That is certainly very favorable stuff. Thank you for all your enthusiasm to present these sort of helpful information here.
Excellently created post, only when all people supplied the same content as you, the net would be a more desirable destination.
I have been unable to enter the sweepstakes on line. Please enter me.
I do consider all of the concepts you’ve presented to your post. They are really convincing and will certainly work. Nonetheless, the posts are too short for starters. May just you please prolong them a bit from next time? Thank you for the post.
Thanks for your marvelous posting! I seriously enjoyed reading it, you may be a great author.I will remember to bookmark your blog and will come back later on. I want to encourage one to continue your great posts, have a nice weekend!
Very informative and superb body structure of content material , now that’s user pleasant (:.