Random password keyboard circuit

In the design, the front panel keys are set to 10 numeric keys from 0 to 9 and
a total of 16 keys including the setting key, the up key, the down key, the confirm key, i the recall key, and the doorbell key j. There is also an internal door opening button in the interior, and a molded button is also designed. When the card reader succeeds in reading the card. The drive relay
is closed, so that Kl and K2 are connected. After 10ms, the relay is closed and Kl and K2 are disconnected, thus simulating the key-connecting action.