Double meter timer circuit (2)

This device can control various household appliances on and off every day. The circuit principle is as follows. AC220V is stepped down by transformer B, then full-wave rectified by diodes D1 and D2, and filtered by capacitor C to obtain a DC voltage of about 14V. This voltage is added to both ends of thyristor SCR1. When meter A outputs an alarm pulse (on ), SCR1 is turned on, relay J1 is energized, its contact J1 is closed, and the timing socket has electrical output. At the same time, the J1-1 contact is closed to prepare for SCR2 to be turned on. When the timing reaches the point, meter B outputs a fixed Alarm pulse (off), SCR2 is on, its contact J2 is disconnected, SCR1 is off, its contacts J1 and J1-1 are both disconnected, the timing socket has no electrical output, and SCR2 is also shut down due to the disconnection of J1-1 and the anode voltage loss. Cut off, J2 returns to the closed state, and the circuit returns to the initial state. Component selection: 1N4001 can be used for diodes D1~D6. The two meters A and B should use electronic meters with alarm output, such as sports watches, speech electronic meters, etc. The alarm signal is derived from both ends of the piezoelectric buzzer, J1, J2 uses 12V relays with a contact capacity of 5A, and ordinary 3A thyristors for SCR1 and SCR2 can be used.