Electronic alarm clock principle description
1. Display principle:
The main part of the display is a 2-digit common red digital tube. The drive is driven by a PNP-type three-stage tube. Each end is equipped with a finite current resistor. The drive mode is scanning, occupying P1.0~P1.6 ports.
The principle of sounding electronic alarm clock
After the gear of the electronic alarm clock is turned to the timing, the protruding portion of the supporting gear slides into the hole of the other gear, and this drop causes the contact to be connected to the circuit. The output audio from the oscillating circuit is driven by a triode amp to boost the buzzer. The switch can be stopped manually, and as the gear rotates, the falling gear will be lifted slowly, the contact will be disconnected and the sound will stop.