Timing control circuit (1)

(1) Introduction to circuit principle This LED digital display timing controller can meet the user's timing requirements for electrical appliances to be switched on and off three times a day. It can be used for timing
spraying for strong bud growth, timing spraying for nursery beds, various timing ventilation, timing sprinkler irrigation and other facilities. automatic timing control.
    The timing controller circuit consists of an input control circuit, a display drive circuit, a reset circuit, a clock oscillator, a power supply circuit and a control execution circuit
, as shown in Figure 3-45.
    The power circuit consists of diodes VD1, VD2, filter capacitors C1, C6, C7. Current limiting resistor R． and backup battery CB.
    The input control circuit consists of function control button Sl, shift/manual control button S2, lift/open button S3, lower/close button S4,
resistor Rz-Rs and timer integrated circuit 1C (including input command detection, clock Oscillation frequency division, counter, display driver, controller and other circuits)
internal circuit composition.
    The reset circuit consists of reset button s5, diode VD3, resistor Ri; and capacitor C3.
    The display driver circuit consists of 4-bit I. Ⅱ) Display (including 1. EDlt-LED4), drive transistors Vl-V4, timer integrated circuit IC and
resistors R6 NRl+d, Ra --R, etc.
    The control execution circuit consists of transistor VT5, relay K, diode VD4, light-emitting diode I.ED5 and resistors Rij, Ri. composition.
    The clock oscillator circuit consists of a quartz crystal oscillator HC and capacitors G and C5.
    After turning on the power. One channel of the +5v voltage provides working voltage for the LED display and the emitters of VT1 ~ VT4 through VD1; one channel
supplies power to the IC through VD2, and at the same time charges the GB through Shu; the other channel supplies the control execution circuit.
    Sl is used to switch the time setting state, travel time setting state and timing setting state of the timing controller. When setting the time state, S2 is used
to convert the adjustment hour or minute. tsa is used to increase the number of time, and double is used to reduce the time.} When setting the timing time state, S2 is used to
convert adjustment hour or minute. In addition, it can also be switched to set whether a certain timing time is working; when setting the travel time state, S2 is used to enter or exit the manual
state. S3 is used to turn on the power of each pair of devices, and S4 is used to turn off the power of the device.
    The Dingwei controller can be set to a working state of three on and one off, or can be set to a working
state of two on and two off (on and off twice a day) or one on and one off.
    When setting the time, press s5 first. Clear and reset the circuit. The LED display star shows "oo:00". First press Sl to make
the hour digit of the LED display flash, then use S3 and S4 to adjust the hour value; then press Sz to make the minute digit of the LED display flash, and use S3 and S4 to adjust the minute
value.
    When setting the scheduled power-on time of the equipment power supply, first press Sl to light up LED1 and LED3 on the LED display, and then use the method of setting
Beijing time to adjust to the required scheduled power-on time; when setting the scheduled power-off time, Press S1 to turn off LED3 (LED1 is still on), and
then use the method of setting Beijing time to adjust the required scheduled shutdown time. If you need to set the timer to turn on and off, you should set two more power-on times
and two more power-off times. After setting the 6 scheduled times (3 scheduled on times and 3 scheduled off times), press Sl to return to
the running time state.
    When the scheduled power-on time arrives, the @ pin of the IC outputs a high level, causing VT5 to conduct; K pulls in. Its normally open contact turns on
the working power of the load (electrical equipment), and LED5 lights up at the same time; when the scheduled shutdown time arrives, the @ pin of the IC changes to low level, causing v and rs to cut off, and K
is released. The working power supply of the load is cut off by the normally open contact of K, and I and ED5 go out.