Powerline Filter/Surge Suppressor

Jon Risch has designed an effective powerline filter to remove some of the noise carried on the AC line. It can be built either as a simple filter or a MOV can be added to make a powerline filter with a modicum of protection from voltage spikes. Countless number of Inmates at AA have built these and report that they outperform most commercial units. The schematics for both versions are shown at the right (Click Photo to Enlarge) For details see Jon Risch's web site.

In building these units, it's important to use the parts that Jon calls out, especially the powdered iron inductors (J.W.Miller #5520, a 100 uH,10 amp) and the AC rated capacitors. Subsitution of these parts may degrade the performance of the unit or, worse, cause an electrical hazard.

The inductors for this project are nearly impossible to find. Last year, the Inmates of AA did a group buy which enabled many of us to try these units. Here's one of the surge suppressor versions that I built into an anodized extruded aluminum box. I also built one with two filter circuits in the same box, giving me separate filters for the analoge and digital portions of my system in the living room where there's not room for balacned power transformers. n building these units, it's important to pay attention to the parts layout for best and safest operation.

The inductors should be mounted at least a half-inch away from the metal enclosure. The capacitors should be mounted as clost to (actually mounted ON) the IEC socket and the outlets. The MOV in the surge suppressor version should be mounted as close to the IEC socket and circuit breaker as possible and its wires kept as short as possible to decrease the loop inductance of the MOV circuit.

DO NOT leave out the ciruit breaker in the version with the MOV, it's function is vital for protection from fire in the event that the MOV suppresses a powerline spike
To the right is a pictoral diagram of how the unit is contructed. Click Image to Enlarge

Click to Enlarge

For those unable to find the components, a complete kit of parts,including a pre-cut anodized enclosure is available from DIYCable.com.

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