Today we will introduce the functions, structure and functions of eleven classic NE555 application circuit diagrams.
NE555 Touch Timer Switch Circuit
The integrated circuit IC1 is a 555 timing circuit, which is connected here as a monostable circuit. Usually, because there is no induced voltage on the P-side of the touch chip, the capacitor C1 is discharged through the 7th pin of the 555, the output of the 3rd pin is low, the relay KS is released, and the electric light is not lit.
When it is necessary to turn on the light, touch the metal piece P by hand, and the clutter signal voltage induced by the human body is added from C2 to the trigger end of 555, so that the output of 555 changes from low to high level, and the relay KS pulls in, the electric light point bright. At the same time, the 555 pin 7 is internally cut off, and the power supply charges C1 through R1. This is the beginning of timing.
When the voltage on the capacitor C1 rises to 2/3 of the power supply voltage, the 555 seventh foot channel causes C1 to discharge, so that the output of the third pin changes from the high level to the low level, the relay is released, the light is extinguished, and the timing ends.
The timing is determined by R1 and C1: T1=1.1R1*C1. According to the values indicated in the figure, the timing time is about 4 minutes. D1 can be used with 1N4148 or 1N4001.
NE555 Automatic Curtain Circuit
The circuit uses a mixture of transistors, integrated circuits and a relay, and is used for a pair of curtains that automatically open and close. Using the switch S3 also allows manual control to make the curtains only partially open or closed. The circuit controls a motor connected to a simple pulley mechanism to move the curtains.
Automatic operation The circuit can be divided into three main sections, a bistable latch, a timer and a commutation circuit. The toggle switch S3 determines the manual or automatic mode. The circuit shown above is drawn in the automatic position and operates as follows. The bistable built-in Q1 and Q2 and related circuits and control relays are around A/2. S1 is used to open the curtains and S2, closing the curtains. At power-up, a brief positive pulse is applied to the base of Q2 through C2. The second season will be in and activate relay A/2. The networks of C3 and R4 form a low current hold circuit for relaying. Relay A/2 is a 12V relay with a 500 ohm coil. It takes a little less flow to operate it than it does, keeping it powered. Once the relay has been actuated, the current through the coil is reduced by R4, saving power consumption. When Q2 is turned off, C3 will be released, but when Q2 is activated (either at the switching power supply or by pressing S1), capacitor C3 will charge very quickly through the relay coil. The initial charging current is sufficient to energize the R4 relay and the current is sufficient to keep it energized.
NE555 Water Open Alarm Circuit
The water opening alarm is composed of a temperature control circuit, a low frequency oscillation circuit and a high frequency oscillation circuit. RP, RT and VT1 form a temperature control circuit. The low frequency oscillating circuit composed of IC1, R2, R3, and C1 has its forced reset terminal 4 controlled by VT1. A high-frequency oscillator composed of IC2, R4, R5, C2, etc., whose forced reset terminal 4 is controlled by IC1. When the water temperature reaches a certain temperature, the resistance value of RT becomes smaller, VT1 is cut off, IC14 pin is high level, IC1 starts to oscillate, output low frequency pulse, modulate the high frequency oscillator composed of IC2 to work, and emits drip-drop sound.
NE555 Triode Identification Circuit
In the figure, 555, R1, and C1 form a multivibrator, and the 555 output terminal 3 is charged and discharged by R1 through R1, and the other circuit supplies the base voltage to VT1 via R3. When pin 3 is high, C1 is charged and VT1 is turned on. When pin 3 is low, C1 is discharged through R1 and VT1 is turned off. LED1, LED2, R5 are used as the power supply voltage of the measured transistor C and b, and the discharge end 7 of 555 is connected to the e pole of the tube under test. Let LED1 be red and LED2 be green. When measuring the NPN type triode, the red LED flashes, indicating that the tube is good. If the red and green LEDs are not lit, it means that the c and e poles are open, or the b, c or b, e poles are shorted or open. When measuring the PNP type triode, the green LED flashes, indicating that the tube is good, otherwise it indicates that the c, e pole is open, or b, c or b, e is short or open.
In the figure, components such as 555, R1, R2, and C1 constitute an audio oscillator. R3 and RP are the bias current resistance of the tube to be tested. Adjusting the RP can make the sound bigger or smaller. If the NPN type test tube is inserted without sound, the tube is bad. Adjusting the RP sound does not change much, indicating that the beta value is low. Adjusting the RP sound is large, indicating that the beta value is high. If the PNP type transistor is tested, connect R3 with the positive terminal to the power ground. The original C point is inserted into e, and the original e point is inserted into c.
NE555 Infrared Remote Control Delay Light
Modern homes generally have an infrared remote control, and we can use an existing remote control to control an infrared remote control delay light. In the figure, H is an integrated infrared receiving head, and C1 is a filter capacitor. Since the remote controller sends out a series of digital pulses, after C1 filtering, a negative going pulse is obtained to make the 555 monostable circuit work.
NE555 Infrared Remote Control Switch Light
In the figure, IC1, R1, C2 and other components form a monostable circuit. Components such as IC2, R3, R4, R5, and C3 form a bistable switching circuit. R3 and R4 are connected to IC22 and pin 6. R5 and C3 are connected to the output of IC2, and are connected to pins 2 and 6 through relay contacts. When the contacts are open, since both pins 2 and 6 are 1/2 VDD, the output is random when the power is turned on. If pin 3 is high, when the relay is pulled, the charging voltage on C3 is added to pins 2 and 6. Since the charging voltage is higher than the trigger level 2/3VDD, IC2 is reset and the 3 pin is turned Low level. At the same time, because the on-chip discharge tube is turned on, the 7-pin is low level and the LED is bright. When the relay contact is turned on and off, regardless of whether C3 discharges to the 3 pin through R5, it does not affect the state of the circuit, and the 3 pin is still low. When the remote control is pressed again, the relay is again sucked, because the discharged C3 is connected to pins 2 and 6, so that IC2 is set, the 3 pin is high, the internal discharge tube is cut off, and the 7 pin is high. Extinguished. The circuit is in another steady state.
NE555 Light Control Stair Light
In the case of strong natural light during the day, if the corridor lights are still on, it is a great waste. This experimental circuit can solve this problem, when the natural light reaches a certain illumination, the voice control function is invalid. The circuit principle is: Photosensitive resistors RG and R7 form a voltage divider circuit. When the illuminance is strong, the RG resistance value becomes smaller, the 5554 foot potential becomes lower, and the output terminal 3 is always 0. When the illuminance is weak, the resistance of RG becomes larger, and the potential of 5554 becomes higher. At this time, the monostable circuit is controlled by the negative pulse signal of 5552.
NE555 dual audio doorbell
Dual audio can emit “ding” sounds of two different frequencies. Usually, the 5554 pin is grounded through R1 and C1, the 555 is in the reset state, the 3-pin output is low, and the speaker is silent. When K1 is pressed, VDD charges C1 through VD1, causing the 5554 pin to quickly go high and 555 to start oscillating. At the same time, VDD provides working voltage to the R3, R4, and C2 oscillating networks through VD2. At this time, R2 and K1 and VD2 are in parallel circuit, R2 resistance becomes smaller, 555 oscillating frequency becomes higher, and (叮) sound is generated. When K1 is released, since the charge on C1 is discharged through R1, the 5554 pin is still high, and 555 will remain in an oscillating state. At this time, the network composed of R2, R3, R4, C2, etc. makes the oscillation frequency low. Produce (咚) sound. As C1 is gradually discharged, until the 5554 pin is low, the 555 is reset again, the oscillation stops, and the speaker is silent.
NE555 water level (motor switch) controller
In the figure, 555 constitutes a Schmitt trigger to complete the water level control function. The working principle is as follows: A, B, and C in the drawing are three detection points. When the water level rises to point A, the pump stops. When the water level is lower than point B, the pump works and automatically adds water to the pool.
Point C is at the bottom of the pool. It is connected to the power supply VDD. When the water level is lower than point B, the voltage of 5552 and 6 is 0, the output of 3 feet is high, VT1 is turned on, the relay is closed, and the pump works.
When the water level reaches point B, the points C and B are short-circuited under the action of water, so that the voltages of pins 2 and 6 are equal to R3/(R3+R2+R1)*VDD, which is equal to 1/2VDD (2.25V). This voltage is greater than 2 feet (1/3) VDD, less than 6 feet (2/3) VDD, 3 feet remain at the same level, continue to add water.
When the water level reaches point A, the three points C, B, and A are short-circuited, so that the voltage of pins 2 and 6 is equal to R3/(R3+R2)*VDD, which is equal to (3.6V). This voltage is greater than 6 feet (2/3) VDD, 3 feet output low level, VT1 is off, the relay is off, so that the pump stops working.
Telephone self-control delay lighting controller circuit composed of NE555
A typical circuit of a telephone self-controlled delay lighting controller composed of a NE555 type time base integrated circuit is shown in the figure. The controller does not work during the day, and the lighting fixture automatically lights up when the phone rings at night or picks up the phone. After the call is terminated for 1 minute, the lighting fixture can be automatically turned off. It is often used for public telephone or home answering, and telephone lighting control.
NE555 audio control delay off circuit
The 555 voice-controlled delay desk lamp circuit is composed of multiple uses, and is mainly composed of a photoelectric coupling circuit, a light control circuit, a negative pulse generating circuit, a monostable trigger circuit, a thyristor switching circuit and a power supply circuit.
IC1 selects the 4-pin PC817 model; IC2 selects the NE555 equivalent type time base integrated circuit. VT is best to use 9014, 3DK4 and other switching tubes; VS selects 1A, 600V ~ 800V bidirectional thyristors, such as 97A6, 97A8 and other models; regulator tube is 1/2W12V such as 2CW60. MG selects models such as MG45 with bright resistance less than 1kΩ. C5 is best to use CBB poly propylene capacitors, withstand voltage of 400V or more. H uses a 25W or 45W bulb.
When the bell rings or picks up the phone at night, the light will automatically light up. After the hang up, the 45s light will turn off automatically. It can be used as a general dimming table lamp.
The 330K adjustable resistor is a dimming potentiometer without a switch. When using the delay light, just press the delay button and touch the button S, the light will be turned off after 45 seconds.