Back in the day a display motor device was available. It consisted of a pivoting mechanism driven by a solenoid
The arm would swing thru and arc, driven by the solenoid until power was cut by a microswitch, prn
Anyone have either the name or source? Thanks
A "display motor device"? I'm puzzled as to exactly what you need. Simply put, a solenoid is is an electromechanical/electromagnetic device consisting of a coil of wire around a sliding or movable magnetisable metal. When power is applied, electromagnetism causes the metal to suddenly move in one direction or another. You mention of a moving arm suggests that the operation needs to be somewhat slower than a solenoid's operation.
There are many ways of moving and arm ranging from servo motor, stepper motor, rack and pinion, piece of string around a shaft, etc., etc.
We had one when I worked in BT. It was a novelty display in a reception area. The arm waved back and forth and a small strip of led's spelled out words & figures as it moved. Retinal image persistence meant you were able to "see" something that was no longer there as each column of each character was displayed by the single stack of about 10 LED's. It was fascinating to watch.
Aha! It is that type of sign, and LED type. I was thinking of something else. They were a fad a few years ago. The Internet no help? Are you trying to repair one or make one? There are also those that connect to a bicycle wheel and show pictures as it rotates. Banggood has some, I think.