Power a sign without tangling wires
How do you power a rotating sign without tangling the wires?
The answer to have a rotating or revolving power source is a slip-ring and brush assembly. In a standard lighted sign, you would run your power cord up through the sign pole to the lights inside the sign. Most times this would be a 3-wire power cord with hot, neutral, and ground, here in the US we usually use 115VAC power. The display rotator is placed between the sign pole and the sign frame. (see illustration below)
When the shaft turns so does the slip ring and the wires. The rings are made of bronze and they conduct electricity to the wires.
The brush assembly is stationary along with the sign pole, and the box frame. the incoming power connects to the brushes; one wire per brush. The brush has a brass housing and a copper, spring-loaded brush. the brush conducts electricity. Incoming power connects to each brush which connects to the corresponding ring. Electricity travels up the sign pole to the brushes, passes through the brushes to the rings, and then through the electrical wires up though the rotator shaft and into the sign to the lights. The brushes are in constant spring loaded contact with the rings so there is always power even as the rings are turning. The wires don’t actually move, they simply turn with the shaft.