This is the circuit diagram of Battery Charger Circuit using LM311
and SCR. It works on the principle of controlling the switching of an SCR based on the charging and discharging of the battery. In this circuit, SCR acts as a rectifier as well as a switch to allow the rectified DC voltage to be fed to charge the battery. If the battery gets fully charged, this situation is detected using a comparator circuit and SCR is turned off.
Get the enlarged circuit diagram, working and applications of this circuit by reading the post: 9v Battery Charger Circuit using LM311 and SCR