Kellogg GD929B computer-type dual-temperature mini water dispenser circuit

The working principle of the circuit shown in the figure below is as follows:

When the power is turned on, the 220V mains power undergoes RI, Cv1 step-down and current limiting, VD1~VD4 full-wave rectification, C1 and C5 filtering, and VS1 voltage stabilization to obtain a 12V DC voltage, which is supplied to the control circuit. IC1 is the core of the control circuit. The 12V DC voltage is reduced to 4.3V through R4, VS2, VT1 and other components for IC1 to work. Pins 3 and 5 of IC1 are connected to ground, pins 16 and 5 are connected to the crystal oscillator, and pin 18 is connected to the positive terminal of the power supply through R7. After the power is turned on, the indicator LED-P is lit and other circuits are on standby. After adding water to the water dispenser, press the switch key K3, and the circuit starts to work. Pin 2 of IC1 outputs a high level, causing the transistor VT2 to conduct, and the relay JZ1 is closed. The heater is energized and starts heating. Pin 1 of ICl is controlled The thermostat is grounded and remains closed. At the same time, pin 10 of ICl is low level, and the heating indicator LED-J is on; pin 13 of IC1 changes to high level, driving VT3 to conduct, and buzzer BE1 makes a sound. When the water boils, the thermostat trips, IQ pin 1 becomes high level and pin 2 becomes low level, VT2 is cut off, JZ1 is released, and the heater stops heating. At the same time, pins 10 and 8 of IC1 both output high level, the heating indicator LED-J goes out, and the heat preservation indicator LED-B is lit, indicating that it has entered the heat preservation state.

The reboiling program of the water dispenser works in the same way as the heating. When the reboiling switch K1 is pressed, pin 6 of IC1 receives the trigger signal and switches to high level. IC1 starts timing internally, pin 2 changes to high level, and the reboiling program starts running (time is about 1 minute).

When you need to start the timing function, press switch K2, and the timing time has three time periods: 2h, 4h, and 6h. When the timing time is not reached, the corresponding timing indicator light (such as LED-4) lights up. Once the internal timer is reached, the power supply is automatically turned off.

In fields such as industrial control and instrumentation, LEDs are also widely used as indicator lights and working status indicators. LED indication has the earliest application time, the application circuit is relatively simple, safe and reliable, and it will still be an area that cannot be ignored in future LED applications.

Figure 1 Kellogg GD929B computer-type dual-temperature mini water dispenser circuit