Author Topic: Open Hardware EMC Test Equipment  (Read 563 times)

0 Members and 1 Guest are viewing this topic.

Offline wilhe_jo

  • Contributor
  • Posts: 45
  • Country: at
Open Hardware EMC Test Equipment
« on: June 09, 2020, 03:45:56 pm »
Hi all!

I'm currently building test equipment for my EMC related business.
Now I was wondering if anyone needs a small 9k-30MHz LISN?

I opted to roll my own instead of going to get a Tekbox one because I wanted to be able to measure L/N simultaneously with a scope in addition to the traditional use of an EMC receiver.

If there's demand I'll tidy up my documentation and maybe put together something like a kit to make DIY easier.

BTW, I intend to do the same for all boxes filled with "some copper and a lot of air" that are used for EMC testing :)
So CDNs are next...

vy 73
 
The following users thanked this post: 2N3055, little.tesla

Offline fcb

  • Super Contributor
  • ***
  • Posts: 1627
  • Country: gb
  • Test instrument designer/maker G1YWC.
    • Electron Plus
Re: Open Hardware EMC Test Equipment
« Reply #1 on: June 10, 2020, 09:42:31 am »
We built our own LISN prior to buying one.  It's not that difficult - but you have to find a way to characterise it for it to be 'useful'.

If I was building another one, then I would probably include a relay to kick in to discharge the line caps - I've been bitten by those more than once!

Also, a LISN without a clean AC source is pretty useless.
https://electron.plus Power Analysers, VI Signature Testers, Voltage References.
 
The following users thanked this post: prasimix

Offline wilhe_jo

  • Contributor
  • Posts: 45
  • Country: at
Re: Open Hardware EMC Test Equipment
« Reply #2 on: June 10, 2020, 12:22:06 pm »
The nice thing is, that today you have cheapish things like the VNWA and the nanoVNA.

Both seem to be pretty capable in doing this.
Well, I'm just in the progress in doing all measurements with these devices and compare them... ;)
The final calibration adapter is in the works, though.
Of course, I'd add the calibration information to the documentation.
This is a lot of work, however.

That's why I'm asking if there's demand...
I quit my day job and got self-employed because I was fed up with doing work all-day long and nobody cared :)

I'm just in a new office, so I did not investigate the "ambient" noise level, yet.
However, you need to use an isolation transformer anyways (preferably a shielded one).
In addition, my LISN has the 250┬ÁH inductor as well.
The CISPR16-1-2 standard suggests a minimum isolation of 40dB from 50kHz.
With the usual 20dB from a transformer you should not have too many problems, at least for 150k-30M measurements.

I made my design pretty universal.
It should be pretty straight forward to put 2 of the PCBs in the same enclosure and have the first one form an additional filter if needed
The CISPR 16 series would also allow for something like this.

But you're right, an ac-voltage source is quite beneficial.

73
 
The following users thanked this post: little.tesla

Offline prasimix

  • Supporter
  • ****
  • Posts: 1490
  • Country: hr
    • EEZ
Re: Open Hardware EMC Test Equipment
« Reply #3 on: June 29, 2020, 04:22:18 pm »
We built our own LISN prior to buying one.  It's not that difficult - but you have to find a way to characterise it for it to be 'useful'.

If I was building another one, then I would probably include a relay to kick in to discharge the line caps - I've been bitten by those more than once!

Also, a LISN without a clean AC source is pretty useless.

I'm in process of building one by myself since I failed to pass "radiated emission" test. Could you please elaborate more how your build differs from ready made one?

Offline fcb

  • Super Contributor
  • ***
  • Posts: 1627
  • Country: gb
  • Test instrument designer/maker G1YWC.
    • Electron Plus
Re: Open Hardware EMC Test Equipment
« Reply #4 on: June 30, 2020, 09:51:34 am »
We built our own LISN prior to buying one.  It's not that difficult - but you have to find a way to characterise it for it to be 'useful'.

If I was building another one, then I would probably include a relay to kick in to discharge the line caps - I've been bitten by those more than once!

Also, a LISN without a clean AC source is pretty useless.

I'm in process of building one by myself since I failed to pass "radiated emission" test. Could you please elaborate more how your build differs from ready made one?

How will the LISN help you with radiated emisions?
https://electron.plus Power Analysers, VI Signature Testers, Voltage References.
 

Offline prasimix

  • Supporter
  • ****
  • Posts: 1490
  • Country: hr
    • EEZ
Re: Open Hardware EMC Test Equipment
« Reply #5 on: June 30, 2020, 09:52:47 am »
Sorry, I mean conducted as described in mentioned thread.  :phew:


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf