Peterson Goodwyn

Creating RFI/EMI for testing
« on: January 03, 2013, 04:02:49 PM »
I'd like to get a feel for how well the various EMI/RFI suppression schemes I blindly implement in every circuit are working. How can I generate some interference?


JohnRoberts

Re: Creating RFI/EMI for testing
« Reply #1 on: January 03, 2013, 04:29:07 PM »
Spark gap...

JR

PS: Linear amps for CB radios, cell phones, etc.
Don't only half-ass tune your drums. Visit https://circularscience.com to hear what properly "cleared" drums sound like.

Speedskater

Re: Creating RFI/EMI for testing
« Reply #2 on: January 03, 2013, 05:51:02 PM »
For a long time we would was a "clacker" to test new circuits.

To make a "clacker", start with a robust power-line AC relay. Wire the Neutral to the coil, then connect the other end of the coil to the normally closed relay contacts then through a loop of heavy stiff wire (about a foot or so in diameter) and finally to the Hot wire.  Plug this bay in and ic goes CLACK, CLACK, CLACK.  It generates a huge amount of EMI/RFI.

(I wonder if I still have the engineering test report)
Kevin

dmp

Re: Creating RFI/EMI for testing
« Reply #3 on: January 03, 2013, 05:53:50 PM »
Wiring up a dimmer switch next to you test bench?
This is something you'll likely run into if you are setting up to record in different spaces, and can wreak havoc.


abbey road d enfer

Re: Creating RFI/EMI for testing
« Reply #4 on: January 03, 2013, 06:22:13 PM »
Just your cell phone. Everytime you call or you're called, it produces a couple watts of certified garbage.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

gemini86

Re: Creating RFI/EMI for testing
« Reply #5 on: January 04, 2013, 12:44:08 AM »
Ever play a tele with a cell phone in your pocket, right behind the pickups?
- Rodney

"...you better call Kenny Loggins, 'cause you're in the danger zone."

alexc

Re: Creating RFI/EMI for testing
« Reply #6 on: January 04, 2013, 05:20:27 AM »
CRT monitor? Always made a truck load of close proximity noise for me!

A soldering iron nearby -  I used that in interference tests many times.

Maybe a CB radio or some other kind of radio transmitter  :)

Microwave oven!
I ping therefore I am

gemini86

Re: Creating RFI/EMI for testing
« Reply #7 on: January 04, 2013, 05:59:53 PM »
Any kind of AC motor would make a bunch of 60Hz noise as well.
- Rodney

"...you better call Kenny Loggins, 'cause you're in the danger zone."

dmp

Re: Creating RFI/EMI for testing
« Reply #8 on: January 05, 2013, 10:05:10 AM »
A banjo might make some unpleasant noise!  haha

(I kept waiting for someone to make a banjo joke)

p.s. why were there no banjos on Star Trek? It was the future

s2udio

On the end of a Rural Twisted Pair.


Re: Creating RFI/EMI for testing
« Reply #10 on: January 12, 2013, 07:51:47 PM »
An unshielded DC-DC / switching converter...

J
Prepare yourself. You are about to become the voice of Interplanetary Parliament.

a soBer Newt

Re: Creating RFI/EMI for testing
« Reply #11 on: February 07, 2013, 06:49:45 PM »
I was doing ribbon mic transformer noise measurement with a Helmholtz coil at work the other week. 



And here is with just a 120V 240V transformer.


 

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