Electronic Circuits and electronic circuits, electronic schematics plus an extensive resource for hobbyists, inventors and engineers

DiscoverCircuits.com has links to 45,000+ electronic circuits, cross-referenced
into 500+ categories.    We have searched the web to help you find quick design ideas.

HOME Schematics Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches
Welcome to DiscoverCircuits.com - online since 2002

See Media Kit for
Advertising Opportunities

Attention Designers:  Please alert us by eMail if we have linked to sites
where your original material has been copied without your permission.
We will change to the LINK to your site.  
Thank you.

 

Alarm Circuits
Alarms:  #'s       A - C       D - G       H - L       M - Q       R - T      
U - Z

 

Last Updated: October 24, 2017 02:54 PM

 

Circuits Designed by Dave Johnson, P.E.

Human Footstep Alarm   -  This circuit processes the amplified signals from the footstep detector circuit and activates a microprocessor when the circuit detects footsteps.  At has an adjustable sensitivity . . . Circuit by David A. Johnson P.E.-July 11, 2006

Indicates when it is Time to Dust   -  I have used the circuit below for many different applications, which require ultra low power drain.  It uses a single CA4013 flip/flop.  One section forms a pulse generator.  The generator produces 100uS pulses at a rate of about 1 per second . . . Circuit Solution by Dave Johnson P.E.-July 06, 2000

Indicates when it is Time to Dust   -  I thought about this circuit when I heard that a lot cleaning personal in hotels were either dusting rooms more often than necessary or not enough.  I have not yet built and tested this circuit completely but in concept it should work . . . Circuit by Dave Johnson P.E.-July 06, 2000

Indicator for Bad Light Bulb   -  This request came from a Discover Circuits visitor.  He wanted to turn on a LED indicator light whenever a circuit detected a burned out tail/brake light on a car or truck.  The circuit shown below uses a transistor switch, to detect current flowing through a low value resistor . . . Hobby Circuit designed by David Johnson P.E.-December 17, 2006

It's Time to Dust Indicator   -  I thought about this circuit when I heard that a lot cleaning personal in hotels were either dusting rooms more often than necessary or not enough.  I have not yet built and tested this circuit completely but in concept it should work . . . Hobby Circuit designed by David A. Johnson P.E.-July 06, 2000

Knocking rings Doorbell   -  in some apartment buildings and homes, not equipped with a door bell, it may be hard to hear someone knocking on the front door.  The circuit below provides a means to activate a loud beeping sound inside, whenever someone knocks on the door . . . Hobby Circuit designed by David A. Johnson P.E.-June 14, 2009

Light/Dark Activated Motion Detector   -  This circuit can sound an alarm when the shadow of a hand or arm moves over  two small photo diodes . . . Circuit by David Johnson P.E.-August 21, 2005

Low Voltage 120vAC Power Line Alarm   -  This circuit will turn on a beeper when the line voltage drops below 100 volt AC.   . . . Circuit by David A. Johnson P.E.-July 09, 2006

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

Head Light Alarm -  "Never forget to turn off your head light ever again!  Most newer cars already have this feature built-in but there are still lots of cars out there without it.   This simple circuit is cheap and can be built for about $5 bucks!" __ Designed by Tony van Roon  VA3AVR

Headlight Reminder for Cars -  Ever forgotten to turn your car's headlights off? This device could save you from a flat battery. __ SiliconChip

High Resolution Battery-Powered Robust Type K Thermocouple Signal Conditioning Amplifier with Cold Junction Compensation -  The circuit is used as a plug-in adapter for common digital multimeters and is completely portable.  This circuit employs the LT1025 thermocouple compensator to improve accuracy over a wide range of ambient conditions and is mounted close to the thermocouple connection points for optimal thermal tracking.  It precludes the need __ Linear Technology/Analog Devices App Note, Apr 8th 2010

High Resolution Type S Thermocouple Digitizer with Improved Cold Junction Compensation -  This simple interface circuit that demonstrates the practicality of direct thermocouple connection to the LTC2400 using low output voltage thermocouples (a Type S thermocouple, as shown, produces a full-scale output voltage of 18mV).  This circuit uses the LT1025, a micropower thermocouple cold junction compensator, to sense __ Linear Technology/Analog Devices App Note, Apr 8th 2010

High Temperature Alarm -  The high temperature alarm will beep and LED blinks when the temperature of the device increases abnormally.  This simple over heat alarm is to monitor heat generating devices such as motor, inverter etc.  The circuit is a simple astable multivibrator using the low power CMOS timer IC 7555 which is the low power version of the __ Designed by D Mohankumar

High Voltage/Current & Temperature Monitoring -  The LTC2990 is used to monitor system temperatures, voltages and currents. Through the I2C serial interface, the device can be configured to measure many combinations of internal temperature, remote temperature, remote voltage, remote current and internal VCC. The internal 10ppm/°C reference minimizes the number of supporting components and area required. Selectable address and configurable functionality give the LTC2990 flexibility to be incorporated in various systems needing temperature, voltage or current data. __ Linear Technology/Analog Devices App Note, Oct 26th 2010

Highway Alert Signal Lamp -  Here is a signal lamp for safe highway driving.  The lamp automatically emits brilliant tricolour light when a vehicle approaches the rear side of your vehicle.  It emits light for 30 __ Electronics Projects for You

Hijack Alarm -  There are two alarms here, be sure to scroll down.  The first circuit was designed for the situation where a hijacker forces the driver from the vehicle.  If a door is opened while the ignition is switched on, the circuit will trip.  After a few minutes delay, when the thief is at a safe distance, the alarm will sound and the engine will fail __ Designed by Ron J

Home Security -  PIC Project  Creating a modular, networked, home control system was greatly simplified by using common 4-wire phone cable with stake-on connectors.  The cable feeds both power and network signals to the various modules.  Each module is made on a single sided circuit board with RJ-11 connectors (for the network/power) along with other connectors as needed.  This eliminates the need for placing power feeds (wall worts) for each of the modules.  The entire system runs on one power feed. __ Designed by Luhan MonatMesa Arizona

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

Hot-Water-Ready Alarm -  Electric kettles turn off automatically when water has boiled.  What if the boiler beeps to alert you when your water has boiled? The tripping sound of the thermal switch may not __ Electronics Projects for You

House Security SystE - M -  Here is a low-cost, invisible laser circuit to protect your house from thieves or trespassers.  A laser pointer torch, which is easily available in the market, can be used to operate __ Electronics Projects for You

Human Footstep Alarm -  This circuit processes the amplified signals from the footstep detector circuit and activates a microprocessor when the circuit detects footsteps.  At has an adjustable sensitivity. . . Circuit by David A. Johnson P.E.-July, 2006

Hum-sensitive touch alarm -  Radiation signals from mains wiring can travel a few metres of distance.  These can be induced by the electromagnetic field in the human body also.  This touch-sensitive alarm is based on generation __ Electronics Projects for You

Implementing a Smoke Detector with the MSP430F2012 -  Smoke Detectors are designed for 3 basic types of system implementations; Standalone, Wireless Connectivity, and Fixed/Wired Connectivity, the first two being battery powered implementations.  Smoke Detectors have 3 main functional blocks; The Sensor and Signal Chain, Processor, and the Communication Interface.  Where the processor and communications interface typically are not needed in your very basic standalone detectors __ Designed by Texas Instruments App Notes, 18-Sep-06

Indicates when it is Time to Dust -  I have used the circuit below for many different applications, which require ultra low power drain.  It uses a single CA4013 flip/flop.  One section forms a pulse generator.  The generator produces 100uS pulses at a rate of about 1 per secondCircuit Solution by Dave Johnson P.E.-May, 2006

Indicates when it is Time to Dust -  I thought about this circuit when I heard that a lot cleaning personal in hotels were either dusting rooms more often than necessary or not enough.  I have not yet built and tested this circuit completely but in concept it should work. . . Circuit by Dave Johnson P.E.-June, 2000

Indicator for Bad Light Bulb -  This request came from a Discover Circuits visitor.  He wanted to turn on a LED indicator light whenever a circuit detected a burned out tail/brake light on a car or truck.  The circuit shown below uses a transistor switch, to detect current flowing through a low value resistor . . . Hobby Circuit designed by David Johnson P.E.-December, 2006

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

Inexpensive LED Drives Flash & Beep -  06/05/97 EDN-Design Ideas Sometimes, you need an alarm that is both audible and visible in an application that's stingy with space, power, and budget.  The circuit in Figure 1a is compact, efficient, and inexpensive.  The F336HD flashing LED (part no.276-036 at Radio Shack) is a useful device.  It operates directly from 5V and produces a consistent pulse of light at approximately 1 Hz without a time-constant capacitor. __ Circuit Design by Dennis Eichenberg, Parma Heights, OH

Infrared Alarm Barrier -  This infrared alarm barrier can be used to detect persons passing through doorways, corridors and small gates.  The transmitter emits a beam of infrared light which is invisible to the human eye.  The buzzer at the output of the receiver is activated when the light beam is interrupted by a person passing through it.  Infrared __ Designed by Popescu Marian

Infrared beam barrier / proximity Detector -  This circuit can be used as an Infrared beam barrier as well as a proximity detector.  The circuit uses the very popular Sharp IR module (Vishay module can also be used).  The pin nos.  shown in the circuit are for the Sharp & VIshay modules.  For other modules please refer to their respective datasheets.  The receiver consists of a 555 timer IC working as an oscillator at __ Contact: http://www.tronicszone.com

Infrared beam barrier/ proximity sensor -  his circuit can be used as an Infrared beam barrier as well as a proximity detector.  The circuit uses the very popular Sharp IR module.  The pin nos.  shown in the circuit are for the Sharp module only.  For other modules please refer to their respective datasheets __ Designed by Radioland.nt.au

Infrared Beam Break Detector -  Application An infrared detector that sounds a buzzer when an IR beam is broken, meaning the IR signal is lost.  A pulsed IR signal generator is necessary, but not included in this post.  This project would be ideal for doorways or hallways to alert when someone enters or exits an area.  Description The IR sensor responds to __ Designed by Popescu Marian

Infrared beam door alarm -  No circuit description, schematic only __ CdS Electronic

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 Proiximity Detector using a CA3240 -  Schematic only __ Designed by va3iul

Internal Temperature Sensor -  The LTC2997 is a high-accuracy analog output temperature sensor. It converts the temperature of an external sensor or its own temperature to an analog voltage output. __ Linear Technology/Analog Devices App Note, Jul 7th 2011

Introduction to acoustic thermometry -  04/21/11  EDN Technical Article: Use an ultrasonic transducer to measure air temperature in an olive jar. __ Circuit Design by Jim Williams, EDN's most revered contributor, passed away in June 2011 after a stroke.  He was 63.

Introduction to Acoustic Thermometry -  Linear Technology AN131 __ Designed by Jim WilliamsApr 26th, 2011

Intruder Alarm

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 SystE - M -  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

Invisible Infrared Alarm -  This circuit uses invisible infrared light to detect the movement of people through the door.  A short beep will be generated when the infrared beam breaks.  So it is ideal to monitor the passages in shops, banks etc where many people are moving.  Two Infrared LEDs always emit continuous infrared beam to the Photodiode.  The IR __ Designed by D Mohankumar

It's Time to Dust Indicator -  I thought about this circuit when I heard that a lot cleaning personal in hotels were either dusting rooms more often than necessary or not enough.  I have not yet built and tested this circuit completely but in concept it should work . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2000

      >>>

Alarms:  #'s       A - C       D - G       H - L       M -Q       R - T       U - Z

 


Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches



 About Us   |  Advertise on DiscoverCircuits.com   |   Report Broken Links  |    Link to DiscoverCircuits.com  |   
Privacy Policy


Discovercircuits.com endeavors to credit original designers.   Please alert us by eMail so we can
delete links to material that have been copied without your permission
.   Thank you.


© Copyright of all original material on this website is the property
of David A. Johnson, P.E. (Dave Johnson & Associates ) unless otherwise noted.  

Linking is ALLOWED but COPYING any content or graphics to your web site is EXPRESSLY PROHIBITED.
All material is provided "as is" without guarantees or warranty of any kind, either expressed or implied.