Abstract: A security timer, add-on device, for an automated, electrically-powered, garage door causes the door to close after it has been opened for predetermined time, e.g., four and a half minutes. The security timer consists of a relay, two micro switches, bell wire, and electrical wire. The relay, in parallel with the electric light, which is controlled by the automatic electric garage door opener, is thus energized, i.e., the points are opened, when the light is energized. Thus, the normally closed (N/C) relay opens and remains open while the light is lit. The first micro switch (M/S), normally opened (N/O), is in series with the relay, and is attached to one of the points of the relay, the other end, of the M/S, is attached to a push-button wall switch, which can also be used to control the garage door openings or closings. This M/S has a whisker which comes in contact with the door when it is fully open; thereby closing the M/S.