Re: Noise Filtering Capacitors

Posted by TxGoat On 2023/6/19 22:03:43

I used to have issues with radio static in very dry weather caused by static discharge through the front wheel bearings. The tires rolling on pavement caused the static charge buildup.

The weather and the road surface would affect the noise. In some cases, patched sections of the roadway would not cause the static, while the unpatched sections would.
The cure was to put a device in the front hub caps that made good electrical contact between the wheel assembly and the chassis. This usually was a spiral bronze spring with a contact button that fit into the center drill hole in the front spindle.

I haven't had that problem in years, and I have not seen one of the devices on any newer vehicle. It may be that tires with steel belts do not need them, or that modern wheel bearing lubricants are non-dielectric. (?)


A generator without a filter capacitor can cause radio static, as can most any brush type motor or generator.

Alternators can produce a whine, and fuel injection systems can generate AM interference.

Poorly-grounded antennas and body panels cause a lot of AM radio interference.