Use NE555 to make a three-way lantern controller

The three-way lantern controller circuit made with NE555 is shown in Figure 3-14. The circuit mainly consists of time base circuit, transistor resistance- capacitance charging frequency divider and relay control circuit.     In the figure, the time base integrated circuit A is connected to an astable multivibrator with an adjustable duty cycle. Adjust the potentiometer RP1 so that the duty cycle is 2:1, that is, the output pin 3 of A outputs a high level for a period of time when the output is low. 2 times the level time. When pin 3 outputs low level, the internal discharge tube of A is turned on, pin 7 outputs low level, the indicator LED 1 lights up, relay K1 is powered on, and the first set of colorful lights lights up; when pin 3 outputs high voltage Normally, the internal discharge tube is cut off, pin 7 is left floating, Kl is released, and LEDI is off. At this time transistor VTI is turned on, LED2 is on, K2 is closed, and the second set of colored lights is on; while the second set of colored lights is on, , the positive voltage at pin 3 of the time base circuit charges capacitor C3 through potentiometer RP2, causing the voltage at both ends of C3 to increase continuously. When the voltage rises to about 1.3V, VD8 and VT2 are connected, LED3 lights up, and K3 Suction table, the third set of colored lights is lit. At this time, the left end of R2 is clamped to low level by diode VD9, VT1 is cut off, LED 2 goes out, and K2 is released. Adjusting the potentiometer RP2 can change the charging rate of the capacitor C3, so that the conduction time of VT2 is equal to 1/2 of the high-level time of pin 3 of the time base circuit, which can ensure that the lighting time of the three groups of colored lights is the same.