Review on 12V 0.5A 6W AC DC Switching Power Supply Adapter For CCTV Security Camera - UL Listed by Larkeese Casiano

This power source has a critical design flaw. I found a 7% voltage drop from the advertised 12V. The unit was most likely rated at 12V before they added the EMI bead (also known as a ferrite bead or similar component). The poorly designed placement/size causes a voltage drop with a subsequent drop in power.Any DC power cord can work like an antenna if it is not modified. Ferrite beads work by providing resistance to squeeze the signal preventing interference (noise) from other devices (radios, appliances, etc).In properly designed units the ferrite bead is wrapped around the capacitor and is internal to the power block itself. I believe they found ringing and added this is after.I would not recommend this product. I will always avoid chargers with an external EMI bead now that I have this understanding. I own two other 12V .5amp power sources without the external ferrite bead that work perfectly. Hope this helps someone.