Motorbike Alarm

This simple to build alarm can be fitted in bikes to protect them from being stolen. The tiny circuit can be hidden anywhere, without any complicated wiring. Virtually, it suits all bikes as long as they have a battery. It doesn't drain out the battery though as the standby current is zero. The hidden switch S1 can be a small push-to-on switch, or a reed switch with magnet, or any other similar simple arrangement. The circuit is designed around a couple of low-voltage MOSFETs configured as monostable timers. Motorbike key S2 is an ignition switch, while switch S3 is a tilt switch. Motorbike key S2 provides power supply to the gate of MOSFET T2, when turned on. 

When you turn ignition off using key S2, you have approximately 15 seconds to get off the bike; this function is performed by resistor R6 to discharge capacitor C3. Thereafter, if anyone attempts to get on the bike or move it, the alarm sounds for approximately15 seconds and also disconnects the ignition circuit. During parking, hidden switch S1 is normally open and does not allow triggering of mosfet T1. But when someone starts the motorbike through ignition switch S2, MOSFET T2 triggers through diode D1 and resistor R5. Relay RL1 (12V, 2C/O) energises to activate the alarm (built around IC1) as well as to disconnect the ignition coil from the circuit. Disconnection of the ignition coil prevents generation of spark from the spark plug. Usually, there is a wire running from the alternator to the ignition coil, which has to be routed through one of the N/C1 contacts of relay RL1 as shown in Fig.1 Fig.2 shows the pin configurations of SCR BT169, MOSFET BS170 and transistor BC548.

Circuit diagram :

 Motorbike Alarm Circuit Diagram

Motorbike Alarm-Pin Configurations :

Pin configurations of BT169, BS170 and BC548

 

Also, on disconnection of the coil, sound generator IC UM3561 (IC1) gets power supply through N/O2 contact of relay RL1. This drives the darlington pair built around T3 and T4 to produce the siren sound through loudspeaker LS1.  To start the vehicle, both hidden switch S1 and ignition key S2 should be switched on. Otherwise, the alarm will start sounding. Switching on S1 triggers SCR1, which, in turn, triggers MOSFET T1. MOSFET T1 is configured to disable MOSFET T2 from functioning. As a result, MOSFET T2 does not trigger and relay RL1 remains de-energised, alarm deactivated and ignition coil connected to the circuit.  Connection to the ignition coil helps in generation of spark from the spark plug. Keeping hidden switch S1 accessible only to the owner prevents the bike from pillaging. Tilt switch S3 prevents attempt to move the vehicle without starting it. Glass-and metal-bodied versions of the switch offer bounce-free switching and quick break action even when tilted slowly. 

Unless otherwise stated, the angle by which the switch must be tilted to ensure the contact operation (operating angle), must be approximately 1.5 to 2 times the stated differential angle. The differential angle is the measure of the 'just closed' position to the 'just open' position. The tilt switch has characteristics like contacts make and break with vibration, return to the open state at rest, non-position sensitivity, inert gas and hermetic sealing for protection of contacts and tin-plated steel housing. If you find difficulty in getting the tilt switch, you may replace it with a reed switch (N/O) and a piece of magnet. The magnet and the reed switch should be mounted such that the contacts of the switch close when the bike stand is lifted up from rest.

Streampowers

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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

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 isn't quite right. 

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

Streampowers

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Little Door Guard

If some intruder tries to open the door of your house, this circuit sounds an alarm to alert you against the attempted intrusion. The circuit (Fig. 1) uses readily available, low-cost components. For compactness, an alkaline 12V battery is used for powering the unit. Input DC supply is further regulated to a steady DC voltage of 5V by 3-pin regulator IC 7805 (IC2).

Fig. 1: Circuit of the door guard

Assemble the unit on a general-purpose PCB as shown in Fig. 4 and mount the same on the door as shown in Fig. 3. Now mount a piece of mirror on the door frame such that it is exactly aligned with the unit. Pin configurations of IC UM3561 and transistors 2N5777 and BC547 are shown in Fig. 2.

Fig. 2: Pin configurations of UM3561 and transistors 2N5777 and BC547

Initially, when the door is closed, the infrared (IR) beam transmitted by IR LED1 is reflected (by the mirror) back to phototransistor 2N5777 (T1). The IR beam falling on phototransistor T1 reverse biases npn transistor T2 and IC1 does not get positive supply at its pin 5. As a result, no tone is produced at its output pin 3 and the loudspeaker remains silent. Resistor R1 limits the operating current for the IR LED.

When the door isopened, the absence of IR rays at phototransistor T1 forward biases npn transistor T2, which provides supply to  positiveIC1. Now 3-sirensound generator IC UM3561 (IC1) gets power via resistor R5. The output of IC1 at pin 3 is amplified by Darlington-pair transistors T3 and T4 to produce the alert tone via the loudspeaker.

Fig. 3: Back view of the door assembly

Rotary switch S2 is used to select the three preprogrammed tones of IC1. IC1 produces fire engine, police and ambulance siren sounds when its pin 6 is connected to point F, P or A, respectively.

Author : T.K. Hareendran

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Simple Car Battery Voltage Monitor Circuit

This circuit is used to monitor the battery voltage to display a dual-colored LED status of the battery to. If the LED “green”battery voltage exceeds 11.9 volts. If the yellow LED, battery voltage 11.9 to 11.5 volts. If the LED is “red” If the battery voltage below 11.5 volts. You can of course change the trigger points by the trimmer resistors and / or changing the value of the resistors in the divider.

A dual op amp is used as a comparator. The green LED on the board, until the voltage exceeds 11.5 volts. The red LED illuminates when the voltage falls below 11.9 volts to the circuit. Therefore, in the 11.9 to 11.5 volts, both LEDs are on, producing a slightly yellow color. When the voltage falls below 11.5 V, the green LED, and now only the red LED flashes to indicate low voltage.

Electronic Parts List
R1=1K2
R2-3-4=680R
R5=15K
R6=10K
R7-8-9-10=1K
IC1=LM324
D1=5V6 /0.5W Zener
D2-3-4-5=LED
RV1=10K trimmer

Is recommended that multi-shaper for V1 and V2. Muti-trimmer makes it much easier to trigger points to make as a less expensive single-turn trimmer. The trimmer can be completely eliminated if you have access to a range of 1% resistors and has had calculated carefully. You would also want to provide more accurate reference voltage as the common 78L05 regulator.

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4-Digit Alarm Control Keypad

Schematic Diagram

Notes

The Keypad must be the kind with common terminal  & a separate connection for each key. On a 12 key pad  look for 13 terminals. The matrix type with 7 or 8 terminals will not do. On the Support Page you will find details of how to Make Your Own Keypad.

The relay is energized by pressing a single key. Select the key you need to make use of and connect it to terminal E. Select the keys you need to make use of for your security code and connect them to A B C & D. Wire the common lead to R1- and all the remaining keys to F.

When you press E the relay energizes & the 12-volt output moves from the off to the set terminal. The green LED also lights. It provides  visual indication that the alarm is set.

When you press keys "A B C and D" in the right order - the relay de-energizes - & the 12-volt output returns to the "off" terminal. The green LED is also extinguished - to indicate that the alarm is switched off.

The remaining keys - those not wired to "A B C D and E" - are connected to "F". Whenever of these "Wrong" keys is pressed - the tried code entry fails - and the code entry sequence is reset.

With a 12-key pad - over ten 000 different codes are available. In the event you need a more secure code - you could basically use a bigger keypad with more "Wrong" keys wired to "F". A 16-key pad gives over 40 000 different codes. In the event you make a mistake while entering the code - basically start again.

The Support Material for this circuit includes a step-by-step guide to the construction of the circuit board - a parts list - a detailed circuit description - and more.

The same thing happens if "C" or "D" is pressed out of sequence. If "C" is pressed before "B" - or "D" is pressed before "C" - the tried code entry will fail. And the code entry sequence will reset.

Veroboard Layout

 

 

 

 

 

 

 

source by zen22142.zen.co.uk

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24V DC Powered Beeper with 4 Separate Inputs

24v DC is a very popular voltage used in industrial settings. This hobby circuit below was designed to accept four different 24v DC alarm input signals, which are then used to drive a single low power beeper. The beeper is a magnetic type with its own oscillator/driver. The four diodes form an “OR” gate so any one of the four inputs will cause the beeper to make noise. A CMOS version of the popular 555 timer is used to strobe the beeper on and off at about 1Hz.


24V DC Powered Beeper with 4 Separate Inputs 

Source :Streampowers

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Using IC 555 Police Sirine Circuit Diagram

Using IC 555 Police Sirine Circuit Diagram, this is the simple Police Sirine Circuit Diagram. The series of police sirens with 555 ic this is a series of sirens that utilizes two IC 555 as a pulse generator and producing shrill voice.

Both ic 555 respectively build the astable multivibrator circuit and generate output signals with different frequencies. It is intended to be used as one of the high frequency generator or a screeching sound and the other as a regulator of the swing from last shrill voice. If we observe the working principle of this circuit is very similar to a series of modulation fm. Where the shrill sound signal likened to a high frequency signal from the oscillator circuit and control signal swing is the wail of the information signal or input signals that will transmit. This is consistent with the shape of the output signal associated with the loudspeaker, which has an output signal frequency changes in the form of regular meetings wave tenuous.

 Using IC 555 Police Sirine Circuit Diagram

Actually a series of sirens could be simpler than if you use a 556 IC which is a dual multivibrator or equal to two pieces of IC 555. IC 556 has two multivibrator circuit menfaatkan so you can meet the workflow of this siren sound-producing circuit. Or you can also make it by using a combination of multiple transistors. And it could be you do remember the oscillator circuit can be easily made with transistors.

Appropriate image above then:
R1, R2, and C1 is a determinant of the frequency of the signal generated by IC1
R3, R4 and C3 is a determinant of the signal frequency whine
Signals generated by IC1 IC2 pin 5 connected to the control signals intended for the resulting shrieks
Screeching sound signal will swing to follow the control of the output signal IC1
You can do experiments in order to gain more understanding of police sirens this circuit by changing the value of some critical components such as the frequency of R1, R2, R3, R4, C1 and C3.

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Police Lights associate crystal rectifier Project

This circuit uses a 555 timer that is setup to each runn in associate Astable operative mode. This generates a nonstop output via Pin three within the type of a sq. wave. once the timer's output changes to a high state this triggers the a cycle the 4017 4017 decade counter telling it to output consecutive sequent output high. The outputs of the 4017 ar connected to the LEDs turning them on and off.

Schematic

Parts List

1x - NE555 Bipolar Timer
1x - 4017 Decoded Decade
6x - 1N4148 Diode
1x - 1K Resistor (1/4W)
1x - 22K Resistor (1/4W)
2x - 4.7K Resistor (1/4W)
6x - 470 Resistor (1/4W)
1x - 2.2µF Electrolytic Capacitor (16V)
2x - BC547 NPN Transistor
2x - LED (Blue)
2x - LED (Red)
1x - 9V Voltage Battery    Link

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Usng Lm 358 Siren Alarm Circuit Diagram

This is the simple ic based Siren Alarm Circuit Diagram.  This siren alarm circuit may provide the final building block in an alarm circuit using a relay to activate it. This siren circuit is very simple and is constructed using common electronic components .

 Siren Alarm Circuit Diagram

When the switch is pressed C3 charges up through R4 with a time constant of 0.47 seconds and when the switch is released C3 begins a slower discharge through R7 and R3 with a time constant of about 5 seconds. The op amp 358 used in this project is set up as a voltage controlled oscillator.

When the output of the oscillator (pin 7) switches low there is a charge remaining in C1 which holds pin 5 below the switching point. Current through R7 is proportional to the control voltage on C3. This current discharges C1 causing the voltage on pin 5 to rise towards the switching point at a rate proportional to the voltage on C3. When the switching point is reached pin 7 switches high and initially pulls pin 6 high via C1. This causes the op amp to temporarily turn on hard. But C3 quickly recharges through D2 causing the voltage on pin 5 to fall below the switching point and causing the op amp to switch off again.

The positive pulse output from the op amp puts a fixed amount of charge into C2 slightly raising the potential of pin 6. This causes the potential on pin 6 to rise and assist the sharp switch off of the op amp. Also R5 & C2 delay the rise on pin 6 long enough to get a good output pulse.

Sourced By: circuitsproject

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Using IC 555 Burglar Alarm Circuit Diagram

Burglar alarm circuit or Theft alarm circuits are available in several forms. The above circuit was one of that kind using timer IC 555 as the main component. The circuit is very easy to construct and the cost of this circuit is also very less. So we can implement this circuit by our own and install this circuit in our home so that you can improve your knowledge and it also adds protection to your home.

Using IC 555 Burglar Alarm Circuit Diagram

The working of this circuit is very easy to understand.In the above circuit IC 555 was used as a Astable multivibrator.The Astable multivibrator puts out a continuous stream of rectangular pulses having a specified frequency. Thus by using the Astable multivibrator we can produce continuous frequency which was given as input to the speaker which makes an alarm sound in case of any disturbance in its trip wire. Pin diagram of IC 555 was given below for your better understanding.

Now we can see how we can change the Astable Multivibrator to a alarm circuit.In the above circuit the 4th pin (RESET pin) was connected to the ground using the thin strand of copper wire which is used as a trip in this circuit.The function of the 4th pin that it resets the timing interval when it was connected to the ground.

When the wire was connected the Multivibrator cant produce the rectangular pulses of constant frequency.When the copper strand is cut off then the 4th pin will have no connection with the ground.Therefore IC 555 produces the output pulse and which was given as input to the speaker thus it drives the speaker to give a noise which would scare the burglar away.Thus your homemade effective burglar circuit is readySourced by: Circuitsproject

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Home security monitor system Circuit Diagram

This is the Home security monitor system Circuit Diagram. This circuit provides normally open (NO) and normally closed (NC) contacts SI, S2, and S3 to turn on the alarm after a 30 second delay. S4 and S5 operate instantly The CANCEL switch resets the alarm.

Home security monitor system Circuit Diagram

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Motion Detector Light Alarm Circuit Diagram

This is the simple Motion Detector Light Alarm Circuit Diagram. This circuit is very sensitive and can be placed in a room to detect the movement of a person up to 2 metres from the unit.The circuit is basically a high-gain amplifier (made up of the first three transistors) that is turned on by the LDR or photo Darlington transistor. The  third transistor charges the 100u via a diode and this delivers turn-on voltage for the oscillator.  The LDR has equal sensitivity to the photo transistor in this circuit.

Motion Detector Light Alarm Circuit Diagram

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Power Failure Alarm Circuit Diagram

This is a simple Power Failure Alarm Circuit Diagram. While the power is on, the relay is held open but when the power fails the buzzer-circuit contacts close.

Power Failure Alarm Circuit Diagram

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Simple Car alarm Circuit Diagram Using 555 Timer

This is a Simple Car alarm Circuit Diagram Using 555 Timer.In this simple circuit 555 timer produces a guaranteed delay, allowing the driver to deactivate the alarm and the elimination of a control switch vulnerable outside.The RCS prevents triggering a timer timer B, unless B is triggered by timer switches strategically located detector.

Simple Car alarm Circuit Diagram Using 555 Timer

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Digital Door Chimes Delay Circuit Diagram

This is a simple and Digital Door Chimes Delay Circuit Diagram. This circuit with values shown, this simple circuit will permit one operation every 10 seconds or so. Capacitor C1 charges through Rl when the button is released Making Rl larger will increase the delay.

Digital Door Chimes Delay Circuit Diagram

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Simple C-O alarm to foil P S Circuit Diagram

This is a simple Capacitance operated alarm to foil purse snatchers. As long as touch plates (1) are touched together, the alarm is off. If not held for about 30 seconds, the alarm goes off. The circuit can be disabled with switch or by touching the plates (2) The alarm is battery operated by a bicycle horn.

Simple C-O alarm to foil P S Circuit Diagram

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Simple 555 Based Alarm Circuit Diagram

This is a Simple 555 Based Alarm Circuit Diagram.The alarm circuit has a single 555 oscillator/timer (Ul) performing double duty; serving both in the alarm-trigger circuit arid the entry- delay circuit. In this application, the trigger input of IJ1 at pin 2 is held high via Rl. A normally-closed sensor switch, SI, supplies a positive voltage to the junction of R2 and CI, and lights LED1. 

 Simple 555 Based Alarm Circuit Diagram

With both ends of CI tied high, there is no charge on CI. But when SI opens, CI (initially acting as a short) momentarily pulls pin 2 of Ul low, triggering the timed delay circle.At the beginning of the timing cycle, Ul produces a positive voltage at pin 3, which charges C4 to near the positive voltage at pin 3, which charges C4 to near the positive supply voltage.

Transistor Q1 is heavily biased on by R3, keeping its collector at near ground level. With Q1 on, SCRl`s gate is clamped to ground, holding it off. When the delay circuit times out, pin 3 of Ul goes low and ties the positive end of C4 to ground. That turns Q1 off.When Q1 turns off, the voltage at the gate of SCR goes positive, turning on the SCR and sounding the alarm. The delay time is adjustable from just a few seconds (R6 set to its minimum resistance) to about one minute (R6 adjusted to its maximum resistance).

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One IC Based One Chip Chime Circuit Diagram

Build a One IC Based One Chip Chime Circuit Diagram. This circuit uses only one IC, produces a pleasant tone, and sports a single control for adjusting the tone`s chiming rate. IC1A and IC1B form an astable multivibrator, which produces the circuit`s basic tone.

 One IC Based One Chip Chime Circuit Diagram

 

 

The multivibrator`s frequency is: The component values produce a 668-Hz tone. IC1C buffers the multivibrator`s output to the 8- speaker. Current-limiting resistor R2, determines the speaker`s volume. R2 minimum value is 220 . IC1D and IC1E form an asymmetric, astable multivibrator, which adds a chime effect to the circuit`s basic tone. 

The chime effect`s frequency is: R7 gives this rate multivibrator a slowly varying output signal to produce a pleasant decay for the chime effect. IC1F is an inverting amplifier for the chime multivibrator.

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Simple 2 Door Annunciator Circuit Diagram

Security system or alarms such as doorbell and Door Annunciator are most wanted in industries and institutional use. This is a Simple 2 Door Annunciator Circuit Diagram. When the push buttons at either door are depressed, this circuit generates a different tone for each door. Tones are generated by phase-shift oscillator Q1/Q2. Q3 provides tone frequency change by changing the phase-shift network. U2 and U3 are timers for the tones and Q4/Q5 interface the timers with the push buttons. 

Simple 2 Door Annunciator Circuit Diagram

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Digital Electronic Door Buzzer Circuit Diagram

This is a simple Digital Electronic Door Buzzer Circuit Diagram. Affordable simple door buzzers and buzzer systems for door entry security in homes, offices and buildings. When SI is depressed, an initial positive voltage is placed on C2 and the noninverting terminal of Ul. The circuit oscillates at a low frequency. As C2 charges up through R3, a rapid increase in frequency of oscillation results, producing (at SPKR1) a rapidly rising pitched sound. This sound is easily recognized over ambient noise. 

Digital Electronic Door Buzzer Circuit Diagram

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