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Security Circuits including Burglar Alarms

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

Last Updated: December 31, 2017 10:31 AM

Circuits Designed by Dave Johnson, P.E. :
Secret_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

Simple Circuit Wire Security Loop Alarm -  A wire loop is used to protect valuable objects in this alarm circuit.  The circuit is powered by a 9v battery.. . . Circuit by David A. Johnson P.E.-December, 2004

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:

Rain Alarm -  This circuit consumes no current until moisture is detected on the rain plate.  __ 555-Timer

Rain Alarm -  This circuit gives out an alarm when its sensor is wetted by water.  A 555 astable multivibrator is used here which gives a tone of about 1kHz upon detecting water.  The sensor when wetted by water completes the circuit and makes the 555 oscillate at about 1kHz.   __ Designed by Radioland.nt.au

Rain Alarm / Rain Detector -  This rain detector will give you a heads-up the instant it starts to rain, hopefully giving you time to close windows and bring in possessions.  The battery-powered circuit draws virtually no current when the sensor is dry and the current consumption is low when the buzzer is activated so a couple of AA cells will last a long time.  Alternately, a molded power supply with a simple voltage regulator to drop the voltage to 3 volts could be used.  The circuit is basically a handy flasher circuit that operates well on only 3 volts using ordinary silicon transistors.   __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Rain Detector -  This circuit uses a sensor made of a small piece of etched PC board and a simple SCR circuit to detect rain and sound a buzzer.  The SCR could also be used to activate a relay, turn on a lamp, or send a signal to a security system.   __ Designed by Aaron Cake

Relay Based Motorcycle Alarms -  Motorcycle Alarm Circuits:  These are two - easy to build - relay-based alarms.  You can use them to protect your motorcycle - but they have many more applications.  if you use relays with 6-volt coils - they'll protect your "Classic Bike".  Both alarms are very small.  The completed boards occupy about half a cubic-inch - 8 cc.  The standby current is zero - so they won't drain your battery.  __ Designed by Ron J.

Remote Door Lock -  Recently, many cars are equipped with Remote Car Door Controller called Keyless entry.  On this page, I will introduce the equipment which changed a remote control for the engine start into the door lock __ Designed by Seiichi Inoue

Remote Doorbell Warning Switch -  This circuit should only be used with the solenoid type chime doorbells, the electronic type that play tunes will not work here __ Contact IQ Technologies

Reverse warning Device -  Schematic only, no circuit description included __ Designed by Seiichi Inoue

RF Alarm -  This simple circuit is sure to have the police beating a path to your door, however, it has the added advantage of alerting you to their presence even before their footsteps fall on the doormat.  The circuit transmits on Medium Wave (this is the small problem with the police).  IC 1a, together with a sensor (try a 20cm x 20cm sheet of tin foil) oscillates __ Designed by Rev. Thomas Scarborough

RFID Car immobiliser with PIC12F629 -  Ok, so there are heaps of immobilisers out there but with most of them, if someone has your keys, they have you car.  What good is a car alarm with 3+ point immobilisation if someone manages to get the keys and of course the alarm remote.  This is a__ 

RFID Transponder-Low Power -  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 Page

Rolling Code Security System; Pt 1  -  ideal for keyless entry for doors in cars, homes & industry, this Keyless Entry System features a rolling code to ensure high security.  it also has two door-strike outputs, an alarm system & provision to use up to 16 separate keyfob transmitters with the same receiver.__ SiliconChip

Safety-Lock with Telecard as Key -  This safety-lock can be work with up to 8 different  telecards (empty  or not) as access keys.  Each  telecard can be registered or  unregistered from the  system, by press the  corresponding button.   __ Designed by © Vassilis Serasidis

SCR Based Burglar Alarm -  This is a simple SCR based burglar alarm circuit.  its features include automatic Exit and Entry delays - together with a timed Bell cut-off and Reset.  it's designed to be used with the usual types of normally-closed input devices such as - magnetic-reed contacts - micro switches - foil tape - and PiRs __ Designed by Ron J

Secret_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

Secured Room Access System -  Security is a prime concern in our day-to-day life.  And access control system forms a vital link in a security chain.  The microcontroller-based digital lock presented here is an access control system...__ Electronics Projects for You

Security Keypad II -  An improved version that can be used on security vaults, Doors with electric latches, Alarms, Safety devices and many other uses.  it uses an HiTACHI LCD (16x1 or 8x1) and a matrix keypad.  The HEX code is available for 16F84A and 16F628.   __ Designed by Jose Pino

Security Light & Switch with PIR Sensor -  Moderately priced Passive infrared PiR Sensor modules are now widely available.  By using these readymade and pre-configured PiR sensors, even an average electronics hobbyist can construct his/her own Motion Sensor Unit.  The one evening project presented here is based on a common and very popular PiR module SB0061, priced below __ Designed by T.K. Hareendran

Security Light & Switch with PIR Sensor Update -  This is a simple update to Mr.  Hareendranís PiR Sensor Security Light circuit.  it has a shortcoming limits the relay voltage to approximately 3.3 V.  While this may function with some 5V relays, it will not function with all.  The nature of an emitter follower Darlington forces the output voltage to be two junction drops below __ Designed by Jim Keith

Security System Switcher -  An audio signal can be used as a form of input to control any security system.  For example, an automatic security camera can be configured to respond to a knock on...__ Electronics Projects for You

Sensitive Optical Burglar Alarm -  This optical burglar alarm uses two 555 timer IC s.  Both the ICs  are wired as astable multivibrators.  The first astable multivibrator built around IC 1 produces low frequencies, while the second astable...__ Electronics Projects for You

Sensor-Based Door Lock -  The door lock controller given here is a simple electronic switching circuit realised using a low-cost unipolar Hall effect sensor IC MH183.  This CMOS switch IC incorporates advanced chopper stabilisation technology...__ Electronics Projects for You

Shed / Garage Alarm -  This is a simple single-zone burglar alarm circuit.  its features include automatic Exit and Entry delays.  it's designed to be used with the usual types of normally-closed input devices such as - magnetic-reed contacts - micro switches - foil tape - and PiRs.   __ Designed by Ron J

Shed / Garage Alarm -  Battery-Powered Alarm Circuits:  This is a basic single-zone burglar alarm circuit.  its features include automatic Exit and Entry delays - and an optional Siren Cut-Off timer.  it has an extremely small standby current.  This makes it ideal for battery-powered operation.  Use it in your caravan, mobile home, lock-up, or anywhere mains power is not available.  __ Designed by Ron J.

Shop-Door Alarm -  Battery-Powered Alarm Circuits:  Attach this circuit to the door of an unattended shop or reception area - and the sound of the buzzer will tell you when you have a customer.  Add a siren - and it becomes a simple intruder alarm.  The    Page includes a free SiMetrix circuit simulation.  __ Designed by Ron J.

Simple  Suitcase-Lift Alarm -  This suitcase-lift alarm circuit uses vibration sensor HDX-2NC instead of a commercially available sensor.  A home-made mercury switch can also be used instead.  Circuit and working Circuit diagram of the simple suitcase-lift alarm...__ Electronics Projects for You

Simple Circuit combination lock -  This experiment may be built using only one 8-position DiP switch, but the concept is easier to understand if two switch assemblies are used.  The idea is, one switch acts to hold the correct.   __ Designed by © EETech Media, LLC.

Simple Circuit Electronic 'Lock' -  There are six (or more) push switches.  To 'unlock' you must press all the correct ones at the same time, but not press any of the cancel switches.  Pressing just one cancel switch will prevent the circuit unlocking.  When the circuit unlocks it actually just turns on an LED for about one second, but it is intended to be adapted to turn on a relay which could be used to switch on another circuit.  Most relays cost about £2 to £3 extra __ Designed by John Hewes

Simple Circuit 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 SiMetrixcircuit simulation.  __ Designed by Ron J.

Simple Circuit Shop-Door Alarm -  Battery-Powered Alarm Circuits:  Attach this circuit to the door of an unattended shop or reception area - and the sound of the buzzer will tell you when you have a customer.  Add a siren - and it becomes a simple intruder alarm.  The    Page includes a free SiMetrix circuit simulation.  __ Designed by Ron J.

Simple Circuit Transistor Based Motorcycle Alarm -  Motorcycle Alarm Circuits:  This is an even simpler transistor based motorcycle alarm.  The circuit features a timed output and automatic reset.  it can be operated manually using a key-switch or a hidden switch.  By adding an external relay, it will set itself automatically - and/or immobilize the machine - every time you turn-off the ignition.  it's easily adapted for a 6-volt system - so it will protect your "Classic Bike". - Now With Free SiMetrix Circuit Simulation.  __ Designed by Ron J.

Simple Circuit Wire Security Loop Alarm -  A wire loop is used to protect valuable objects in this alarm circuit.  The circuit is powered by a 9v battery.. . . Circuit by David A. Johnson P.E.-December, 2004

Simple Circuit Wireless Security System -  Overview The Simple Wireless Security System monitors the open/closed state of two (garage) doors.  Sensors detect the state of the doors, and a Zigbee wireless transceiver sends the state information to a PC.  The PC runs a GUi__ 

Single Zone Alarm -  A single zone alarm circuit with entry and exit delay and other facilities.   __ Designed by Andy Collison

Single-button lock provides high security -  03/04/99 EDN-Design ideas (contains several designs, scroll to find this one) Figure 1 is the block diagram of an easily programmed, single-button combination lock.  You operate the lock by using a series of short and long pulses from a momentary switch that masquerades as a doorbell button.  The circuit uses inexpensive CMOS logic.  The retriggerable timer, T1, locks out entries made after the T1 code-entry window, thereby greatly enhancing security.  The circuit in Figure 2 operates as follows: The Schmitt-trigger quad NAND gate, IC 1, debounces the code-entry switch and, with the aid of simple analog circuitry, produces separate outputs for activation times of less than and more than 0.3 sec.  These outputs connect to the select gate, IC 5 __ Circuit Design by Maxwell Strange, Fulton,MD

Siren Simulator -  This siren circuit simulates police, fire or other emergency sirens that produce an up and down wail.   __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Six-Zone Alarm with 7 Segment Display -  This alarm system has 6 independent zones, 1 timed entry/exit zone, a 7 segment LED display and a test or walkthrough facility.  Suitable for a small office or home environment, it can also be adapted to use a combination lock or keypad to set and reset the alarm __ Designed by Andy Collison

Smart Loop Burglar Alarm -  Simple loop burglar alarms sound whenever the loop breaks.  What if a clever thief comes to know of the working of this alarm? He may simply short the loop by using...__ Electronics Projects for You

Sound Operated Switch -  This sensitive sound operated switch can be used with a dynamic microphone insert as above, or be used with an electret (ECM) microphone. if an ECM is used then R1 (shown dotted) will need to be included. A suitable value would be between 2.2k and 10kohms. __ Contact IQ Technologies

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


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