RF interference with Arduino

Hello:

Here’s my set up - four transformers (taken out of plasma lamp toys) are activated by information from a Ping sensor and two PIR sensors that is sent to my Arduino running the code. When the transformers are on, they create RF signals that run along conductive paths and light up glass tubes full of gases. All of my components are hanging upside down underneath the paths/tubes in a 19"x24" area…maybe 5" max gap between components.

When the transformers are on and send out the RF signals, it messes with my Arduino and the inputs from the sensors. Basically, everything goes crazy and switches on and off randomly and the information from the sensors is inaccurate…

Any ideas for shielding against RF signals? Tin foil? Anything that I could wrap or place around my Arduino that would stop this interference would be helpful.

Thank you!

Make sure your power supply is properly decoupled, first of all. maybe use a separate supply for the plasma lamp transformers, and opto-isolate the switching signals. Also, put the Arduino in a metal box and connect the box to Ground. Better still have two metal boxes, Grounded, one for Arduino and the other for the transformers

Look up the decoupling link from here:-
http://www.thebox.myzen.co.uk/Tutorial/Introduction.html

In addition to Anachrocomputer’s and Grumpy_Mike’s excellent advice, check the health of your grounds. You need low resistance, low inductance paths to ground. A star ground configuration (i.e. all ground wires run separately to the ground point) would probably be a good idea.

When the transformers are on, they create RF signals that run along conductive paths and light up glass tubes full of gases. All of my components are hanging upside down underneath the paths/tubes in a 19"x24" area…maybe 5" max gap between components.

OK, so, you are deliberately creating RF fields, and ‘broadcasting’ them to your gas …

Have you checked the ‘range’ of your transmission?
Reducing its power to the minimum is going to be helpful to you, and appreciated by the neighbours!
Improving your ‘aerial design’ (like putting a ground ‘plane’ {maybe even non-planar} an appropriate distance behind it) should improve its directionality, and allow you to operate with minimal power. Then you can benefit from shielding your aerial feeds and rf generator circuitry, and also from ensuring that your RF generator isn’t putting RF back out onto its electricity supply.

Regarding the Arduino and its sensors and power supply. Yes, anything {ie everything} vaguely conductive and unshielded/ungrounded in the neighbourhood is going to act as a receiving aerial and pick up your RF transmission. So you need to have everything, cables, the lot, equipped with well-grounded shielding. (But naturally, you don’t want anything accidentally short-circuiting to ground.)
And because people will also act as receiving aerials (hopefully harmlessly, see below), I suspect that any contact sensors may need to be appropriately filtered - in hardware, software, or both.
Did you check the Wikipedia entry on plasma lamps? http://en.wikipedia.org/wiki/Plasma_lamp

The radio frequency field produced by plasma lamps can interfere with the operation of touch pads used on laptop computers, digital audio players, cell phones, and other similar devices. Some types can radiate sufficient RFI to interfere with cordless telephones and Wi-Fi devices several feet away.

And that Wikipedia entry also carries a worthwhile reminder about the potential of a risk to Heart Pacemaker users - if this thing is ever likely to be exposed to the public (and vice versa) there needs to be some sort of warning displayed.

Thank you everyone for your responses…they were all very helpful.

What I ended up with was actually a simple solution…I modified an extension cord (with an earth-ground) by removing the +/- wires, leaving only the earth-ground wire. I attached that to my frame and it took care of everything…there was just too much static building up on the frame.

With the transformers running and the metal frame grounded to earth, my Arduino and sensors work perfectly.

There will be a warning sign up for people with pacemakers…good call!

Thanks again everyone!