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Miniature Loop Alarm - (circuit design added 8/03) |
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Minimizing SUN's Noise in IR Reception - ASCII format (electronic Circuit /
Schematic added 10/04) |
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Modular Burglar Alarm (mba) - This circuit features automatic Exit and Entry
delays and a timed Bell Cut-off. It has provision for both normally-closed and
normally-open contacts, and a 24-hour Personal Attack/Tamper zone. It is connected
permanently to the 12-volt supply and its operation is "enabled" by opening
SW1l...(electronic schematic added 8/02) |
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Modular Burglar Alarm (Ron J) - The Basic Alarm Circuit has an automatic
Exit/Entry Zone, an Instant Alarm Zone that will accept both normally-closed and
normally-open triggering devices, and an "Always On" 24-hour Personal
Attack/Tamper Zone. By using the Expansion Modules, you can add as many extra
alarm zones as you require....(added 05/06/07) |
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Motorcycle Alarm - Any number of normally open switches may be used. Fit the
mercury switches so that they close when the steering is moved or when the bike is
lifted off its side-stand or pushed forward off its centre-stand. Use
micro-switches to protect removable panels and the lids of panniers etc...(circuit
design added 8/03) |
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Motorcycle Alarm No.3 (Ron J) - This circuit features an intermittent siren
output and automatic reset. It can be operated manually using a key-switch or a
hidden switch; but it can also be wired to set itself automatically when you
turn-off the ignition. By adding external relays you can immobilize the bike,
flash the lights etc.....(circuit design added10/05) |
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Motorcycle Alarm Number (Ron J) - This circuit features an intermittent siren
output and automatic reset. It can be operated manually using a key-switch or a
hidden switch; but it can also be wired to set itself automatically when you
turn-off the ignition. By adding external relays you can immobilize the bike,
flash the lights etc. Ron has....(added 10/05) |
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Motorcycle Alarm Number 3 - This circuit features an intermittent siren output
and automatic reset. It can be operated manually using a key-switch or a hidden
switch; but it can also be wired to set itself automatically when you turn-off the
ignition. By adding external relays you can immobilize the bike, flash the lights
etc..(electronic design added 6/07) |
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Motorcycle Alarm Number 4 - This is a simple easy to build transistor based
motorcycle alarm. It's designed to work at 12-volts. But if you change the relay
for one with a 6-volt coil it'll protect your "Classic Bike". The standby current
is virtually zero so it won't drain your battery. (added 10/05) |
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Motorcycle Alarms Numbers 5 & 6 - 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....
(added 10/05) |
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N/O: N/C Timed Burglar Alarm - This is a simple but effective alarm circuit
which can reset its self after a time that you select. it has normally open and
normally closed triggers which make this circuit very practical. This alarm has
normally open and normally closed triggers. It's on a 555 timer so the alarm will
reset it's self after a certain amount of time. The time is adjustable....
(added 10/05) |
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Nocturnal Animals Whisker - A low-rate flashing lamp drives away undesired
visitors Automatic on-off operation (added 9/04) |
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Novel Buzzer - (circuit design added 8/03) |
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One-IC two-tones Siren - This circuit is intended for children fun, and is
suitable to be installed on bicycles, battery powered cars and motorcycles, but
also in models and other games. With SW1 positioned as shown in the circuit
diagram it reproduces the typical dual tone sound of Police....added 4/05) |
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One-Time-Only Burglar Alarm - When this alarm is activated its Siren will
sound once, for up to 20-minutes. Then it will switch off and remain off. The
basic circuit has a single zone with independently adjustable Exit and Entry
delays. This will be adequate in many situations. However, ....(circuit design
added 05/08) |
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Oscillating output improves system security - 02/06/03 EDN-Design Ideas: Many
electronic-control systems have digital outputs that use transistors. One method
of improving the security in these outputs is to use an oscillating signal to
represent a logic-high state instead of a fixed voltage level.... Many
electronic-control systems have digital outputs that use transistors. One method
of improving the security in these outputs is to use an oscillating signal to
represent a logic-high state instead.....(design idea added 09/03) |
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Over Voltage Protection - Safety devices like fuses provide protection against
excess current, but do nothing for transients and short duration spikes of high
voltahe on the power supply lines.This circuit uses the "crowbar" method and
provides fast protection against transient voltage spikes, transients that could
cause damage to sensitive components. (added 08/08/08) |
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Perimeter Monitor - Using a single cable such as speaker wire or doorbell
cable, this circuit can be remotely positioned, for example, at the bottom of a
garden or garage, and used to detect all sound in that area. The cable can be
buried in a hosepipe or duct and is concealed out of sight. The mic is an ordinary
dynamic mic ....(added 8/03) |
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Personal Alarm (Stepan Novotill) - This one is particularly loud even though
it runs on only two AA batteries. It uses a Push Pull transformer output
(added 2/05) |
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PIR Motion Detector - (circuit design added 8/03) |
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Police Siren - This siren circuit simulates police, fire or other emergency
sirens that produce an up and down wail. (added 10/05) |
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Programmable Digital Code Lock - (electronic circuit added 10/05) |
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Proximity Alarm #2 - (circuit / schematic added 2/03) |
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Radio Remote Control using DTMF - NOTE: Fair Warning, Annoying popup.
Here is a circuit of a remote control unit which makes use of the radio frequency
signals to control various electrical appliances. This remote control unit has 4
channels which can be easily extended to 12. This circuit differs from similar
circuits in view of its....(added 6/07) |
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Rain Detector (Aaron Cake) - 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. (circuit / design added 8/03) |
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Remote Door Lock (Seiichi Inoue) - …(circuit design added 05/08) |
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Reverse warning device - The car that is equipped with the reverse lamp. In
the case that it is not equipping, it's a defective car.….(added 05/08) |
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RF Transmitter for PIR Sensors - (circuit design added 8/03) |
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RFID Reader Handheld - Intersil Application Block Diagram (app note
added 6/06) |
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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.….(circuit design added 05/09) |
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SCR Based Burglar Alarm - (electronic design added 6/07) |
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Security CCTV - Intersil Application Block Diagram (app note added 6/06) |
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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. (added circuit 5/06) |
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Shed/ Garage Alarm - This is a basic single-zone burglar alarm circuit. Its
features include automatic Exit and Entry delays. 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.
(circuit design added 05/08) |
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Simple Alarm System - (circuit design added 8/03) |
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Simple 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….(electronic
design added 6/07) |
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Simple 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.....Designed by John Hewes (circuit added 06/07/08) |
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Simple Fire-Door Alarm - This circuit will let you know when something that
should be kept closed, has in fact been left open. Attach it to a Fire-Door. It
will allow you to pass through the door as usual. However, if it's left open for
more than 30-seconds or so, the buzzer will sound. Photo (circuit design added
05/08) |
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Simple Security Wire Loop Alarm - A wire loop is used to protect valuable
objects in this simple alarm circuit. The electronic hobby circuit is
powered by a 9v battery. The alarm beeper is activated if the wire loop is
severed. The standby current is so low that the 9v battery should last for many
years. ….(designed by David A. Johnson) |
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Simple Shop-Door Alarm - 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. Photo (circuit
design added 05/08) |
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Simple Transistor Based Motorcycle Alarm - 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.....(circuit design added 08/08/08) |
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Simpler CMOS Single Zone Alarm - This circuit features automatic Exit/Entry
delays, timed Bell Cut-off and System Reset. It will accommodate the usual
normally-closed input devices (Magnetic Reed contacts, Micro Switches, Foil Tape
and PIRs). And, with a simple modification, a normally-open trigger may be added .
(circuit design added 05/08) |
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Single Button Lock Provides High Security - 03/04/99 EDN-Design Ideas: 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,.....(design idea added 5/03) |
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Single Zone Alarm - This circuit features automatic Exit/Entry delays, timed
Bell Cut-off and System Reset. It has provision for normally-open and
normally-closed switches and will accommodate the usual input devices (Pressure
Mats, Magnetic Reed contacts, Foil Tape, PIRs and Inertia Sensors). (circuit
design added 08/08/08) |
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Single Zone Alarm (Ron J) - A single zone alarm circuit with entry and exit
delay and other facilities. (circuit design added 8/03) |
