About code locks wrote more than once. However, most of them are difficult to repeat. Design suggested by our Bulgarian friends (the journal “Radio Television Electronics”), devoid of this shortcoming. For opening this lock simply insert the key and complete the circuit with the resistor R1 a certain value (it is mounted in the housing of the key). If the resistance will be different from that specified on the schematic, the relay does not work and the lock will not unlock.
Lock in idle mode (no key) consumes Ocala 16 mA and 24 mA with the key.
Relay — 6V, 20 mA. Transistors V1, V3 — low-power silicon, for example, KT315 with any alphabetic index.
Recommend to read
WITH ONE CALL
In your journal in one of the rooms of yesteryear has published an article — "the plug". I must say that the proposed options combined metal dowels rather complicated to manufacture, but...
STEP… IN THE CLOSET
1. In order to achieve maximum capacity of the height of the majority of cases—a Lee, book or kitchen—use as a rule, taller than a man. To get something lying at the top, you have to...
