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by LGarber
Thu Oct 05, 2017 3:35 pm
Forum: General discussion
Topic: EMC emission at 200mhz
Replies: 31
Views: 7381

Re: EMC emission at 200mhz

There is more to this story that I thought might help others. I did finally pass FCC, but the RPi was indeed part of the problem with radiated emissions in the frequency range between 30MHz and 50MHz. I needed to use Laird-Signal Integrity Products 28S2023-0M0 Clip Together Free-Hanging Ferrite Core...
by LGarber
Wed Sep 06, 2017 4:04 am
Forum: General discussion
Topic: EMC emission at 200mhz
Replies: 31
Views: 7381

Re: EMC emission at 200mhz

Apologies to the forum and the good Pi folks, but my problem turned out not to be the Pi. The LED Driver chip that I was using (PCA9626B) had a 50MHz clock speed....
by LGarber
Sun Sep 03, 2017 10:17 pm
Forum: General discussion
Topic: EMC emission at 200mhz
Replies: 31
Views: 7381

Re: EMC emission at 200mhz

I hadn't seen that UL consultation option. That's fantastic! I will post information to that team just to be on the safe side. Thanks for the tip! Nard SDK indeed looks interesting! However it doesn't appear that I'll need it. I convinced work to buy a Spectrum Analyzer and probes for about $700USD ...
by LGarber
Sat Sep 02, 2017 9:15 pm
Forum: General discussion
Topic: EMC emission at 200mhz
Replies: 31
Views: 7381

Re: EMC emission at 200mhz

Thanks. I'm probably not going to be able to keep the runs short because I'm controlling 80 switches and 120 LEDs at distances of up to 100 feet with one Pi. But I did do a bit more reading and discovered that the 50MHz is the rate at which the SD card is read. So one thing I'm going to try is to ru...
by LGarber
Wed Aug 30, 2017 2:07 pm
Forum: General discussion
Topic: EMC emission at 200mhz
Replies: 31
Views: 7381

Re: EMC emission at 200mhz

I just failed EMC testing at UL. I had spikes at the first several harmonics of 50MHz (50, 100, 150, 200, etc...). I improved it somewhat by disabling HDMI by putting /usr/bin/tvservice -o into /etc/rc.local. I did also disable wifi and bluetooth (because I don't need them) in /boot/config.txt. I'm ...
by LGarber
Sun Mar 26, 2017 9:44 pm
Forum: General discussion
Topic: Raspbian with Read-only Root
Replies: 191
Views: 86121

Re: Raspbian with Read-only Root

ejolson and spock rock! I just spent the last 5 hours playing around with psuter's solution https://www.raspberrypi.org/forums/viewtopic.php?f=66&t=173063 because it sounded so slick. But on my NOOBS RPi 3, I couldn't get it to work. Then I went back to spock's script and in 10 minutes I was up and ...

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