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Showing posts with label alarm. Show all posts

Monday, October 20, 2014

How to Build Timer with Musical Alarm

The timer with Musical Alarm use famous CMOS oscillator/divider IC (IC1 ). Although this circuit operates in 9V its standby current drain is very low. The time delay of timer circuit can be adjusted by adjusting the preset VR1. The base of npn transistor T1 is connected to pin 3 of IC1 through resistor R4 and its emitter terminal is connected with pin 2 of melody generator IC (IC2) in order to provide positive supply when adjusted time delay is over.

Timer with Musical Alarm Circuit Diagram

Here the zener diode ZD1 is used as regulator which reduce power supply to required for operation of IC2 i.e. 3.3V. Lastly for music output the output from pin 1 of IC2 is fed to loud speaker via driver transistor and its volume is controlled by preset VR2. For starting the timer power is supplied by pressing switch SW1. Link

Parts list

Resistor (all ¼-watt, ±5%)
R1 = 1.2 MΩ
R2 = 2.2 MΩ
R3 = 56 KΩ
R4, R5, R6 = 1 KΩ
VR1 = 1 MΩ
VR2 = 1 KΩ

Capacitors
C1 = 0.01 µF
C2 = 0.22 µF
C3 = 1 µF/25V

Semiconductors
IC1 = CD4060 (CMOS oscillator /divider IC)
IC2 = UM66 (melody generator)
T1, T2 = BC547

Miscellaneous
SW1 = on/off switch
9V battery
LS1 = 8Ω, 0.5W speaker

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Simple Alarm Residential 5 sectors Circuit Diagram

This is a circuit of an alarm residential sectors 5, or 5 areas that are monitored separately, it also has a panic button, timing system, is powered by the network jointly by battery v. 12. It is very simple and uses only three integrated circuits and transistors.

Simple Alarm Residential 5 sectors Circuit Diagram

Cheap Bicycle Alarm Schematics Circuit

The author wanted a very cheap and simple alarm for some of his possessions, such as his electrically assisted bicycle. This alarm is based on a cheap window alarm, which has a time-switch added to it with a 1-minute time-out. The output pulse of the 555 replaces the reed switch in the window alarm. The 555 is triggered by a sensor mounted near the front wheel, in combination with a magnet that is mounted on the spokes. This sensor and the magnet were taken from a cheap bicycle computer.

Circuit diagram :
Cheap Bicycle Alarm-Circuit Diagram

Cheap Bicycle Alarm Circuit Diagram

The front wheel of the bicycle is kept unlocked, so that the reed switch closes momentarily when the wheel turns. This triggers the 555, which in turn activates the window alarm. The circuit around the 555 takes very little current and can be powered by the batteries in the window alarm. There is just enough room left inside the enclosure of the window alarm to mount the time-switch inside it.

The result is a very cheap, compact device, with only a single cable going to the reed switch on the front wheel. And the noise this thing produces is just unbelievable! After about one minute the noise stops and the alarm goes back into standby mode. The bicycle alarm should be mounted in an inconspicuous place, such as underneath the saddle, inside a (large) front light, in the battery compartment, etc.

Hopefully the alarm scares any potential thief away, or at least it makes other members of the public aware that something isnt quite right.

Caution. The installation and use of this circuit may be subject to legal restrictions in your country, state or area.

Author : Gerard Seuren

Thursday, February 6, 2014

Digital Alarm Clock Using PIC

This project describes a digital clock with alarm function. It uses a PIC16F877 microcontroller to generate an accurate 1 sec delay with Timer0 using Roman’s zero error method. The time is displayed in large size font on a 4×20 character LCD that uses HD44780 display driver. You can synchronize the time with your computer time through a serial port.

Digital Alarm Clock Using PIC Circuit Diagram

The required power is provided through a 9 V wall adapter which is used to obtain a regulated +5 V power supply using a LM7805 IC. The microcontroller runs with a 20 MHz external clock. The backlight of LCD is driven by a PWM output from the microcontroller so that the back light intensity can be varied. The full software written in JAL is available to download. Source Code.

Saturday, November 30, 2013

Automatic Automotive Burglar Alarm

Alarm triggers on after a 13 second delay and stays on for 1-1 Vfe minutes. Then it resets automatically It can also be turned off and reset by opening and reclosing SI.

Automotive Burglar Alarm Circuit Diagram

Monday, November 25, 2013

Fuse Failure Alarm 2 LED

This circuit motivation let somebody see the performance of the equipment,otherwise Check the fuse arrived the circuit.The circuit is insignificant and the power supply voltage of all kinds. It parade with LED, 2-color in single. Which is cathode normal kind,the anode has two separate terminals. If the circuit is functioning accurately LED, it exposed in environmentally friendly colour.

The display is red, at what time the fuse voguish the circuit is damaged.The resistor R1 limits the current to stream through the LED is going on for 2 mA.This is a sufficient amount to do the LED light.If it lowers the R1 down, the LED light up. In the regular action of the circuit and The fuse is not damaged. The zener diode to prevent the green and red LED light up at once.Zener diode prevents the LED is sea green and red illumination at the same time. The high-pitched efficiency LED, whilst connected in the sphere of congruence. The red LED uses high-pressure, so with the intention of single green LED illumination up only. Diodes D3 and D4 command prevent perilous in support of the LED. While the semi cycle denial voltage of the alternating current voltage.However, if the DC supply voltage.I perform not include to application diode protection.

Sunday, November 24, 2013

Alarm Sound with Control Switch

The heart of this circuit is IC No. 555. When the alert sound was working, even though the switch will continue to be the same, the sound still does not stop immediately.But it will stops automatically, when a set time period,Depending on the resistance of R3, the circuit so I set a time period equal to 1M for 1 minute 6 seconds.

Alarm Sound with Control Switch

The output of IC 555 is triggered by a positive voltage on pin 2,when all switches are connected together.When the something switch is cut off pin 2, it will be negative voltage and the trigger IC 555 will stop. The C1, C4 to protects a noise signal from either switch, which may cause the alarm to be up. This circuit can be used with power supply from 5V to 15V depending on relay sure enough.

Saturday, November 23, 2013

Power Supply Failure Alarm

Most of the circuit power supply failure alarm circuits require additional or external power supply. However, this circuit requires no additional power supply. The circuit uses a voltage of 5 volts to 15 volts. To adjust the voltage of this circuit, first connect the power source (5 to 15V) and change the position of potentiometer VR1 until the buzzer buzzer On to Off position.

If the power supply fails, resistor R2 will bias the transistor and the base will turn on the buzzer. Here is a picture series of power supply failure alarm :

Power Supply Failure Alarm Circuit

Sunday, November 17, 2013

Fire Alarm using NE555 and temperature sensor

This is a simple series of fire alarms. In this series used NE555 timer and temperature sensor to detect high temperatures. The working principle of this temperature sensor that is when the temperature is high around the sensor then there is resistance on the sensor to be small.

However if the low temperature then the resistance will be high. If the resistance of small sensors, the voltage supply will be able to flow past the sensor and activate the transistor.

IC1 NE555 as a regulator of the audio frequency. Transistors 1 and 2 are used as a driver IC1. Output (pin 3) of IC1 would trigger a transistor base T3 (SL100), which drives the speaker to produce sound the alarm. Frequency NE555 depending on resistance values of R5 and R6 and the capacitance sensor C2 temperature. When the temperature gets hot, would provide a low resistance so that supply voltage can flow into the base of transistor T1 through a diode D1 and R2.

Capacitor C1 will charge a positive voltage so that it will increase the time when the fire alarm. The greater the value of C1, the greater the positive bias applied to the base of transistor T1 (BC548). T1 collector coupled to the base transistor T2, transistor T2 provides a positive voltage to pin 4 (reset) from IC1 (NE555). Resistors R4 will make IC1 NE555 continued to be active despite no positive voltage flowing.