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Security Circuits including Burglar Alarms

Security Alarms:  #'s - C     D - L     M - Z

Last Updated: December 31, 2017 10:27 AM

Circuits Designed by Dave Johnson, P.E. :

Front End + Power Supply Circuits of the Electric Filed Disturbance Monitor -  This schematic is the power supply and front-end sections of my field monitor, "Electric Field Disturbance Monitor".  The system can detect human and animal motion by the electric fields they disturb . . . Hobby Circuit designed by David A. Johnson P.E.-March, 2002

Hidden Panic Switch -  Design an electronic switch which would be positioned behind a wall at several key positions and would be activated when an adult human hand was pressed against the wall at that position.  The best way to detect the human hand against a wall was with a capacitance switch.  The QTFS3X from Faraday switches looked like a perfect match.  The switch could be powered by a DC voltage down to 3v.  It required only 30ua of current.  It was quite small and would easily fit behind the wall. . . . Dave Johnson, Lubbock TX-DC Magazine - Issue 18 May 2011

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-368-7747




Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

Face Recognition using Raspberry Pi -  To secure our assets and protect our privacy, there is a strong demand for user-friendly biometric security systems.  There are various types of biometric systems that use signatures, fingerprints, voice, hand...__ Electronics Projects for You

Factory Siren -  This circuit produces a sound similar to a factory siren.  it makes use of a 555 timer IC used as an astable multivibrator of a center frequency of about 300Hz.  The frequency is controlled by the pin 5 of the IC .  When the supply is switched ON, the capacitor charges slowly and this alters the voltage at pin 5 of the IC hence __ Designed by Radioland.nt.au

Field-strength meter -  This is a very straightforward circuit.  The first stage acts as a crystal receiver.  Use a germanium detector diode (like 1N34, but AA119 is much more common in Europe) , a silicon one won't do.  The frequency is determined by L and C.  For the FM band VHF, wind a coil 5mm in diameter, 6-8 turns of coated wire 1mm thick.  You can always vary the frequency by spacing the turns a bit looser or tighter.  C is much less critical.  Something around 100p is preferable, though. __ Contact IQ Technologies

Fire Alarm -  in this fire alarm circuit project, a thermistor works as the heat sensor.  When temperature increases, its resistance decreases, and vice versa.  At normal temperature, the resistance of the thermistor (TH1) is approximately 10 kilo-ohms, which reduces to a few ohms as the temperature ncreases beyond 100°C.  The circuit uses __ Designed by Popescu Marian

Fire Alarm -  This circuit warns the user against fire accidents.  it relies on the smoke that is produced in the event of a fire.  When this smoke passes between a bulb and an LDR, the amount of light falling on the LDR decreases.  This causes the resistance of LDR to increase and the voltage at the base of the transistor  __ Designed by Radioland.nt.au

Fire-Door Alarm -  Battery-Powered Alarm Circuits:  This circuit will let you know when something that should be kept closed - has in fact been left open.  if you attach it to say a Fire-Door - it will allow you to pass back and forth freely.  it's only when the door is open for more than about 30-seconds - that the buzzer will sound the alarm.  The    Page includes a free SiMetrix circuit simulation.  __ Designed by Ron J.

Five Zone Alarm -  This is a complete alarm system with 5 independent zones suitable for a small office or home environment.  it uses just 3 CMOS IC 's and features a timed entry / exit zone, 4 immediate zones and a panic button.  There are indicators for each zone a "system armed" indicator.   __ Designed by Andy Collinson

Five-Digit Alarm Keypad -  This is an enhanced 5 digit keypad which may be used with the Modular Alarm System.  This switch will suit the Modular Burglar Alarm circuit.  However, it also has other applications.  The Keypad must be the kind with a common terminal and a separate connection for each key.  On a 12-key pad, look for 13 terminals.  The matrix type with 7 terminals will NOT do.  Choose the five keys __ Designed by Andy Collison

Front End + Power Supply Circuits of the Electric Filed Disturbance Monitor -  This schematic is the power supply and front-end sections of my field monitor, "Electric Field Disturbance Monitor".  The system can detect human and animal motion by the electric fields they disturb . . . Hobby Circuit designed by David A. Johnson P.E.-March, 2002

Fully Automatic Emergency Light -  This simple automatic emergency light has the following advantages over conventional emergency lights: 1.  The charging circuit stops automatically when the battery is fully charged.  So you can leave the emergency light...__ Electronics Projects for You

Garage Light & Security Control -  Useful for vehicle owners, this gadget automatically turns on indoor/outdoor garage lights and raises an alert when an automobile enters the garage.  Assume switch S2 is in ‘on’ (closed) state.  When power...__ Electronics Projects for You

Gate alarm -  Figure 1 represents a cheap and simple Gate Alarm, that is intended to run off a small universal AC-DC power supply.   __ Designed by Andy Collison

Glass Break Detector -  Glass Break Detector can be designed with 3 types of implementations in mind: Standalone, wireless connectivity and Fixed/Wired Connectivity.  The first two implementations are battery operated.  The functional block diagram of the glass break detector is divided into 3 sub-blocks: the sensing block, the processor and the communication interface blocks.  When implementing a basic standalone type of glass break detector, the processor and the communication interface are not needed__ 

GSM Home Security Alarm System with Arduino -  This project deals with the design & development of a theft control system for home, which is being used to prevent/control any theft attempt.  The developed system makes use of an embedded system (comprises an open hardware microcontroller and a gsm modem) based on Global System for Mobile communication (GSM) technology. __ Designed by T.K. Hareendran

Hidden Panic Switch -  Design an electronic switch which would be positioned behind a wall at several key positions and would be activated when an adult human hand was pressed against the wall at that position.  The best way to detect the human hand against a wall was with a capacitance switch.  The QTFS3X from Faraday switches looked like a perfect match.  The switch could be powered by a DC voltage down to 3v.  It required only 30ua of current.  It was quite small and would easily fit behind the wall. . . . Dave Johnson, Lubbock TX-DC Magazine - Issue 18 May 2011

Home Security Project -  The security system application and program offers a simple demonstration of the BASIC  Serial interface.  By adding only a few door and window switches, a transistor, a siren, (see schematic) and a few lines of BASIC  program (see program listing) the interface can become a multi-function security system.  Please note, however, that it is a "barebones" program.  it is left to the reader to fancy it up to their liking.  __ KD5ZUG

iButton electronic lock -  Since iButton DS1990A introduced in market from Dallas Semiconductor (MAXiM) , it has been used in many applications concerning security, access control systems etc.  in this project we will use iButton as a key to an electronic lock.  This electronic lock can use many different kinds of iButtons and can store up to 9 different keys.  One of the keys is the master key and is permanent stored in memory.  With the use of master key we can add or remove slave keys.__ 

Inexpensive Car Protection Unit -  For car protection, custom-made units are available but they are costly.Here’s a circuit to protect car stereo, etc from pilferage that costs less and requires no adjustments in the car but...__ Electronics Projects for You

Infrared Burglar Alarm -  A special feature of this infrared burglar alarm is latching operation.  Also, the circuit is highly sensitive.  The circuit comprises transmitter and receiver sections.  Whenever IR beam between the transmitter and the...__ Electronics Projects for You

Infrared Detector -  This circuit is a simple IR detector for testing IR remote controllers.  The circuit is based on one phototransistor which receives the IR beam.  The NPN transistor works as an amplifier which feeds current to the led.  When this circuit detects IR or light, the LED is on.  So you need to shield the phototransistor from ambient light if you don't want to do your tests in the dark.  The best way __ Designed by Tomi Engdahl

Infrared gate 2 -  This is an infrared gate with two sensors planned to use in the wall in the way behind a door.  it can be applied in a toilet to keep track of that someone is inside exceeding a certain amount of time.  After that time elapsed, the circuit triggers the digital output wich can turn on a ventillator.  The time period the output is turned on can be separately controlled by a second timer. __ Designed by Peter Jakab

Infra-red Level Detector -  Useful for liquids level detection and proximity devices; Up to 50 cm.  range, optional relay operation __ Contact Flavio Dellepiane, fladello @ tin.it

Intelligent Switch -  This intelligent switch circuit enables automatic, switching on of an emergency light system during darkness in the event of mains failure.  The mains power failure condition is detected by the section...__ Electronics Projects for You

Intruder Detector using Laser Torch -  Here is a simple, low-cost intruder detector that uses an invisible laser beam to detect the intruder.  The laser beam is produced using a 3V DC or 4.5V DC laser pointer...__ Electronics Projects for You

Intruder Radio Alert System -  Consider a situation where a burglar has entered your house and snapped the telephone wires, leaving you with no means of communication with the outside world.  in such an emergency, you...__ Electronics Projects for You

Keep Wandering Children & Pet Nearby -  12/02/10  EDN Design Ideas:  The receiver circuit in Figure 1 sounds an audio alarm when the transmitter (Figure 2) moves beyond a designated perimeter.  The transmitter, a voltage-controlled oscillator, operates at approximately 915 MHz in the unlicensed iSM (industrial/scientific/me __ Circuit Design by Tom Au-Yeung and Craig Sakamoto, Maxim Integrated Products, Sunnyvale, CA

KeyLock -  Press four keys in specific order, and relay will turn on for about to 5 seconds and that is it.  But first you must memorize your code following this way: press and hold button (button on pin 3) , so long until LED goes ON.  Now, when.   __ Designed by © Ivica Novakovic

Keypad Access -  Dual programmable keypad code lock.  Open electrical doors with your secret code only!  __ Designed by Michel Bavin

Keypad Combination Lock  -  A digital combination lock using a push button keypad.  The combination can be changed and the lock has an entry delay.   __ Designed by Andy Collison

Keypad Controlled Switch No.2 -  Universal Keypad-Controlled Switches:  This is a simplified version of the 4-Digit Keypad Controlled Switch.  I have modified the design to reduce the complexity of the circuit - and the number of components required.  As a result - the code is somewhat less secure.  However, there should be lots of situations where it will still be adequate.  __ Designed by Ron J.

Laptop Protector -  Protect your valuable laptop against theft using this miniature alarm generator.  Fixed inside the laptop case, it will sound a loud alarm when someone tries to take the laptop.  This highly...__ Electronics Projects for You

LED Sensor -  From the beginning, LEDs are used in many applications for signalization purposes.  For what else can be LED used except for signalization or lighting? You can use it in another way, and some times that may be very useful.  Usual LEDs can be used as ambient light sensors, where LED can be used for signalization or as ambient light sensors.  The idea is very simple, just look at schematic.   __ Designed by ivica.novakovic

Lightning Activated Camera Shutter Trigger -  This circuit is used to trigger a camera's electronic shutter circuit when a flash of lightning is present.  This circuit would also work for photographing fireworks displays or other events involving flashes of light.   __ Designed by G. Forrest Cook

Live-line Detector -  Detects the presence of a live mains conductor; Minimum parts counting __ Contact Flavio Dellepiane, fladello @ tin.it

Locker Alarm -  The locker alarm circuit or cashbox watcher can be used to protect a cashbox/locker from unauthorised access.  This tried and tested design forms a fool-proof, remotely operated alarm/electromagnetic relay driver that receives its control signal from a standard reed switch.  The circuit works off a 12V dc power supply.  After __ Designed by T.K. Hareendran

Locker Guard -  Protect your valuables from burglary using this simple circuit.  it generates warning beeps when someone attempts to open the locked safe.  The warning alarm sounds at an interval of a few...__ Electronics Projects for You

Long-Range Burglar Alarm using Laser Torch -  Laser torch-based burglar alarms normally work in darkness only.  But this long-range photoelectric alarm can work reliably in daytime also to warn you against intruders in your big compounds, etc.__ Electronics Projects for You

Low cost/ Automatic Emergency Light -  The circuit comprises two sections: charger power supply and LED driver. The charger power supply section is
built around 3-terminal adjustable regulator (IC 1) LM317, while the LED driver section is built around transistor BD140 (T2).  in the charger power supply section, input AC mains is stepped down by transformer to deliver 9V, 500mA to the bridge rectifier, which comprises diodes (iN4007x4). __ Contact IQ Technologies

Low Power RFID Transponder -  This is the Grand Prize winner in the design category of the 1993 RF Design Awards Contest.  This entry exhibited both innovative use of RF technology and an elegant implementation of that technology __ Designed by Raymond T. Page, Reprint courtesy of RF Design Magazine

Luggage Security System based on UM3561 melody generator IC -  While traveling by a train or bus, we generally lock our luggage using a chain-and-lock arrangement.  But, still we are under tension, apprehending that somebody may cut the chain and steal our luggage.  Here is a simple circuit to alarm you when somebody tries to cut the chain.  Transistor T1 enables supply to the sound generator chip when the base current starts flowing through it.__ Learning Electronics

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Security Alarms:  #'s - C     D - L     M - Z


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