Keyless lock - electronic theft protection

7-66 - elektor july/august 1982 Out of the enormous variety of ICs produced today, the number that are designed for use in one specific application represents a relatively small percentage. The basis of the circuit here contains an IC that is from this category. It is the LSI 7220 from LSI Computer Systems and fulfils all the functions for an automatic keyless lock system. However, it is possible to use it for domestic purposes, an elec- tronic safe lock, for instance. When fitted to a car, the ignition circuit is immobilised until the correct code combination is entered via a keyboard consisting of 10 or more keys. Other facilities are also available from the IC. A LED displays the condition of the lock (locked/unlocked). A very cunning feature is the fact that the lock combination is set by the constructor. It is also possible to allow another person to drive the car without disclosing the code or even the existence of the system. be a rather fearsome affair and this would be ...