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In this electronic circuit project Open door alarm a very simple 555 timer Open door alarm circuit project can be designed using an linear hall effect device like in this circuit diagram. This 555 timer Open door alarm circuit is based on the TL3103 linear Hall Effect device used for detecting the angle of rotation. The TL3103s are centered in the gap of a U-shaped permanent magnet. Open Door Alarm with 555 Timer Circuit Diagram: This type of circuit can sense the opening of a refrigerator door. When the door opens, a triac could be activated to control the inside light. The figure shows a door position alarm. When the door is opened, an LED turns on and the piezo alarm sounds for approximately 5 seconds. This door alarm electronic circuit uses a TL3019 Hall Effect device for the door sensor. This normally open switch is located in the door frame. The magnet is mounted in the door. When the door is in the closed position, the TL3019 output goes to logic low, and remains low until the d

This is a simple project Using IC NE 555 Voltage Inverter Circuit Diagram.In many circuits we need to generate an internal adjustable voltage. This circuit shows how it is possible to use a trusty old NE555 timer IC and a bit of external circuitry to create a voltage inverter and doubler. The input voltage to be doubled is fed in at connector K1. To generate the stepped-up output at connector K2 the timer IC drives a two-stage inverting charge pump circuit. The NE555 is configured as an astable multivibrator and produces a rectangular wave at its output, with variable mark-space ratio and variable frequency. This results in timing capacitor C3 (see circuit diagram) being alternately charged and discharged; the voltage at pin 2 (THR) of the NE555 swings between one-third of the supply voltage and two-thirds of the supply voltage. Voltage Inverter Circuit Using IC NE555  The output of the NE555 is connected to two voltage inverters. The first inverter comprises C1, C2, D1 and D2. These c

Enter values for R1, R2, and C and press the calculate button to solve for positive time interval (T1) and negative time interval (T2). For example, a 10K resistor (R1) and 100K (R2) and 0.1 uF capacitor will produce output time intervals of 7.62 mS positive (T1) and 6.93 mS negative (T2). The frequency will be about 70 Hz. R1 should be greater than 1K and C should be greater than .0005 uF. Scroll down page for basic 555 information (pinout and two basic circuits). Positive Time Interval (T1) = 0.693 * (R1+R2) * C Negative Time Interval (T2) = 0.693 * R2 * C Frequency = 1.44 / ( (R1+R2+R2) * C)  First introduced by the Signetics Corporation as the SE555/NE555 about 1971.Pin connections and functions: (See schematic below for basic circuits) Pin 1 (Ground)     - The ground (or common) pin is the most-negative supply potential of the device, which is normally connected to circuit common when operated from positive supply voltages. Pin 2 (Trigger)    - This pin is the input which causes t

This simple ON OFF touch switch circuit is based on the well known timer IC 555 (IC1), which drives a relay that acts like a switch. The metal surfaces can have what form we want, but it should be clean and very close to the circuit. Read more  WC fan using 555 Touch plate MP1 in order to close the contact of relay RL1 [ON], or plate MP2 in order to open the contact of RL1 [OFF]. The Led D2 turns on when the contacts of RL1 are closed. Two small pieces of metal can be used as sensor plates. 555 ON/OFF Touch Switch Schematic     Parts List R1 = R2 = 3.3M R3 = 10K R4 = 1K C1 = 10nF D1 = 1N4007 Q1 = BC547 IC = NE555 12V relay Sourced By: Circuitsstream

This metal detector electronic project schematic circuit is designed using a simple 555 timer integrated circuit . As you can see in the schematic circuit , this metal detector electronic project requires few external electronic parts . This circuit detects metal and also magnets. Metal Detector with 555 Timer Circuit Daigram When a magnet is brought close to the 10mH choke, the output frequency changes. This metal detector project can be powered from a power supply that can provide an output DC voltage between 6 an 12 volt . If a metal is closer to the L1 coil , will produce a change of output oscillation frequency, that will generate a sound in the 8 ohms speaker

 Emergency Lamp With 555 is a single option representing lighting trendy the route of electrical power outages. With Emergency Lamp Sequence 555 uses a 12VDC voltage source with the aim of can stay provided from your 12V battery. Emergency Lamp 555 Sequence With these incredibly very regular and tranquil to make up as every of the components simply to hand from the souk place. Emergency Lamp Sequence With this special 555 can flip to the light 5W-10W.  Emergency Lamp with 555 Timer The circuit is residential with the astable multivibrator simultaneously with the IC 555 with the intention of is certainly employed to mendrive transformer by way of Q1. intended for specially details is often viewed very well within the sequence Emergency Lamp With 555 follows. Functioning frequency range of 555 Emergency Lamp With this specific arrange of configurations R1, R2 and C2. T1 in sequence Emergency Lamp With 10V 500mA 555 is in fact a transformer. Secondary element (0-10V) is connected on b

The Travel Touch Alarm can be used to provide a audible alarm  when someone touches the door knob or handle of your hotel room. The door knob or handle must be made of metal for the circuit to work. The main chip in the circuit is a 555 timer which will be triggered if a hand comes close to or touches the door knob. 555 Timer Travel Touch Alarm Circuit Diagram The circuit attaches to the door knob at the end of the 1 meg ohm resistor. Once the timer is triggered the LED will light and the UJT will output a tone to the speaker. The timer will time out in 5 seconds. The sensitivity of the trigger can be changed by changing the 1 meg ohm resistor to another value. The 5 second time out can be adjusted by changing the value of the resistor connected between pin 8 and pin 7. The output tone can be changed by changing the RC values on the base of the UJT.

This is a 555 led flasher circuit this circuit will blink many LEDs and give rotating effects. The circuit is very easy to build, 555 timer IC is very common now a days you will find it easily. The circuit uses only 3 volt to perform its task, small 3 volt button cells can also be used and it will last longer because the circuit has low current consumption. Upper 555 IC in the circuit is used as multivibrator and the lower 555 IC is working as a trigger pulse inverter.  Source http://www.circuitdiagram.org

A magnet is placed on the door and a magnetic reed switch on the door casing so when the door is closed the circuit is disabled. When the door is open, the LED flashes VERY BRIGHTLY—when closed, the circuit is disabled in such a way that it draws virtually no current for maximum battery life. Door Ajar LED Light Schematic Bill of material 555 door ajar BOM How it works The flasher is the standard 555 oscillator circuit that drives an ultrabright white LED for daylight visibility. Repetition rate is about 2hZ and the duty cycle is about 10%. Peak LED current is 60mA, but average is 6mA. Since the door is supposed to remain closed most of the time, the circuit power is controlled by a 2N7000 N Channel MOSFET. When the reed switch is closed (sensing the magnet), it shorts out the gate drive signal to the transistor and turns off the oscillator. At this time the battery drain is only 9uA. Note that there seems to be no convenient way to turn off the 555 in such a way that it does not draw

This is a simple timed beeper circuit diagram of beeper using 555 timer. This circuit can be employed to energize lights, horn, or other signaling device at any desired interval when the mercury switch is triggered. Since the current handling capability of mercury switch is not so high, an SCR is used to handle current drawn by the 555 timer circuit . Chose the SCR  current rating of 500mA at minimum to safely drive the 555 IC and the relay. The relay is not needed when the current drawn by alarm is less than 200mA, in this case the alarm can be installed to directly replace the relay coil.  Here is the schematic diagram of the circuit. 555-IC Timed Beeper Circuit Diagram

In most WCs with an extractor the fan is connected to the lighting circuit and is switched on and off either in sympathy with the light or with a short delay. Since toilets are sometimes used for washing the hands or just for a quick look in the mirror, it is not always necessary to change the air in the smallest room in the house. The following circuit automatically determines whether there really is any need to run the fan and reacts appropriately. No odour sensor is needed: we just employ a small contact that detects when and for how long the toilet seat lid is lifted.   On-Demand WC Fan Using 555 circuit diagram If the seat lid is left up for at least some presettable minimum time t1, the fan is set running for another presettable time t2. In the example shown the contact is made using a small magnet on the lid and a reed switch mounted on the cistern. The rest is straightforward: IC2, the familiar 555, forms a timer whose period can be adjusted up to approximately 10 to 12 minutes

A very simple electronic key code lock circuit that require few external components can be constructed using this schematic diagram . This electronic key code lock circuit is based on a common 555 timer circuit and some other common components . This low cost key code circuit use six switches that needs to be pressed to open the lock, but only two switches at a time. In many other , more expensive electronic circuits the key code is formed by pressing some switches one by one , not like in this case two switches . If you don’t like to press two switches in the same time you can eliminate one switch , but in that case the code can be more easy to guess by someone ells .Thus a total of three sets of switches have to be pressed in a particular sequence. (Of these three sets, one set is repeated.) An essential property of this electronic code lock is that it works in monostable mode, i.e. once triggered, the output becomes high and remains so for a period of time, governed by the timing c