EMC compliance testing

Not in the US. Don't forget that you also need to meet the Low Voltage Directive ( safety ) too to apply the CE mark.

Pre-compliance testing is a good idea, especially if you're new to it all. I chanced up on a semi-retired emc expert who we use from time to time. Last time, I think he charged about £300/day and brought the necessary equipment to us. You'll need to find a suitable location for certain tests too that's 'rf benign' e.g. has no steel in the construction of the building and isn't near anything like that. We used a hut in a playing field.

Graham

Where I used to work they book a test facility for half a day for preliminary testing. It isn't expensive. That usually shows up one or two problems with emissions which are easily fixed and the equipment generally passes fist time after that.

Leon

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Leon Heller, G1HSM

The device will be powered by USB or a 9-volt wall wart. It's my understanding that it doesn't need Low Voltage Directive compliance if it's under 75 VDC and the external power supply is itself approved. Is that right?

Anyone know where I can find someone like this in California? I'm new to this and it'd be nice to have some hand-holding. And if it's someone willing to give a break to a very small startup company, that'd be even better.

Scott

And would the company provide their own engineers for the testing, or does that come with the facility? I'd like to talk to someone who's been through the whole testing cycle - there's a lot I don't understand about the test setup, especially when it comes to adding cables and connecting the device under test to other devices.

Scott

Household. There would certainly be some commercial/industrial usage, but more often hobbyists in a home environment.

Power will be supplied through USB connection (5 volts) or external supply for standalone operation - generally an off-the-shelf 9v wall wart I expect. Maximum input voltage would be maybe 14 volts. The majority of the internals will run at 3 volts. Haven't chosen a regulator yet, but it won't be anything elaborate. No plans for internal batteries at this point.

It could connect to a PC through USB or RS-232, GPS receiver through RS-232, and VHF or UHF radios through an audio cable. It's got an SD/MMC flash card slot for removable storage.

Thanks,

Scott

it's

Everything needs consideration to the LVD. Just because the supply to your equipment is SELV (not 75V by the way) it does not mean that your equipment is 'safe'. A simple example is the camping fluo lamp. This works off a 12V car battery but powers a fluorescent tube that is often cold cathode struck and requires an output of several hundred volts.

However if you are confident (and expert) enough to verify that the equipment will not 'step up' the incoming SELV , or the user will have no access to a voltage above SELV, then just declare it as such.

After telling us the corner specifications, we could introduce you to the required tests.

Is the device for industrial / household / medical applications ? Is it powered from the powerline / batteries / external power supply ? Is it connected to other stuff ? By what connection ? Serial ? What is the highest internal voltage ? < 48V ? > 48V ? line ?

Rene

--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

Ahhh - OK - then no need for LVD.

If you're new to it, the hand holding is invaluable. I've used that consultant I mentioned since ooohhh 1987 and I've leant many of the tricks of the trade from him.

Good luck looking. I just asked around and got lucky.

Graham

By only using low voltage to be supplied from external, you already offloaded the power line spike tests. Next then is radiated and conducted emission as well as radiated and conducted susceptibility to RF from DC to

3GHz. There, your working device with its standard connectionsis subject to 1) radiation in the mentioned frequency range on cable or through the antenna. The device has to keep on working. 2) the radiation of your device on cable as well as on cable is measured and some values not to be exceeded.

Power and signal lines can be made to conform by shorting the RF to the case with 100nF caps for DC and smaller ones depending on the signal frequency. Oops, household cases are usually not from metal.

Industrial metal cases have to be earthed.

Household cases are usually from plastic, this is somewhat harder to shield.

Rene

--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

I recently used UL for just the FCC Class B and paid about that amount, which was the lowest fee I have ever paid for this testing. I think UL just added this service recently. Up to now we used independent labs. Jeff

This will be a metal case - either steel or aluminum, still working with the enclosure vendor on that. It'll add a few dollars to the price compared to a plastic case, but I think it'll be worth it. Aside from the shielding, there's marketing value in providing a sturdy, durable enclosure. Too many products these days are cheap and fragile.

I saw some mention of having a ground (earth) connection to the case through a screw that serves no other purpose - i.e., not a screw that holds the case on. I don't remember who's requirement that was - might have been a UL thing, and I'm not sure if it's applicable.

I will certainly have plenty of decoupling on the power and signal lines. I hadn't given any thought yet to the electrical connection with the case. I suppose it'll just have the ground plane exposed around the screw holes. I'll ask my PCB and enclosure vendors how they usually set that up.

Thanks...

Scott

Someone was just telling me that UL was outrageously expensive, but maybe that was for their usual safety testing. I suppose they try to sell you their other services as well?

Scott

I'll check them out.

I think you're right. Part 15 doesn't specify any immunity requirements, though it does say something about the device having to accept any interference caused by other devices.

Thanks,

Scott

Undoubtedly !

The last lab I used for conformity testing was ETL Semko in the UK. They weren't too bad on price but hopeless as regards understanding the cable connections for a practical test. That's especially difficult with a product like an audio mixer as I was submitting, where you can have so many possibilities - you just have to make a sensible compromise between minimal and absurdly out of the world possibilities.

I notice they are represented in the USA too.

Worth a call I reckon. Explain that you need FCC and CE at the same time and there should be minimal extra cost. They just need to run some tests with slightly different limits. CE requires immunity though - which I believe FCC still doesn't ( not sure it can require so, given it's role in the regulatory structure - but pls correct me if I'm mistaken ).

Graham