Review on 🔒 12 Pcs Black Ferrite Choke Cable Rings, Roctee EMI RFI Noise Filter Snap-On Noise Suppressor Clips for 7MM Diameter Wire - Electronic Ferrites Core by John Goerge

My new DVR was interfering with my car's FM radio stations or was not available at all. I've tried to connect the power and ground of the camera's power supply to different places with no success. So, through a lot of research, I found that ferrite cores can help reduce unwanted line noise. A total of 6 wires were needed, 4 per 12VDC side. power / ground and 2 after the adapter to the camera cable. My theory is that the 12V DC power supply lacks the signal isolation/filtering quality, so it creates EMI noise that the car stereo picks up.