Electronics, compared to electrical appliances are low powered logical devices, which uses digital signals of 1s and 0s to represent voltage range. The evolution of these devices have promoted information technology from high quality digital signal transmission to recorded speech platform.
Speech signals could not be recorded before the electronic era, it was only disseminated from one person to another to converted to text for easy and uncorrupted information transfer.
The sheave wheel is a pulley wheel that sits above the mine shaft. The hoist cable passes over the sheave wheel and then down the shaft of the mine. (copied from google)
