Controller for keyboard actuated electromagnetic lock - uses three circuits connected to different keys, one giving an immediate alarm, second enabling third circuit which decodes key sequence

摘要

The electromagnetic lock controller using a keyboard for access has additional functions such as a doorbell, closing of the door, or an intercom, incorporated on the keyboard. The keys forming the door opening combinations are connected to circuits of three different types. A first group of keys are coupled through a common link to a 'negative' security circuit which sounds an alarm and inhibits the remainder of the circuit if one of the 'negative' keys are touched. The second group of keys enable the decoder circuit which accepts a coded entry from the keyboard and activates the lock opening mechanism if the correct code is entered. If a wrong combination is entered through the second group of keys, an alarm is triggered. A switch permits permutation of the connections between the keys of both groups as well as the enable keys to of the respective group.