Alarms of all kinds, electronic circuits, Page 5

Alarm Circuits Page 5
Alarms: #-C D-G H-O P-R S T-U V-Z
Last Updated on: Monday, October 03, 2011 06:07 PM

Circuits Designed by Dave Johnson, P.E. :

Security Loop Alarm - A wire is looped through various objects which are to be monitored. The loop wire is typically an aircraft cable but could also be any insulated stranded wire. The loop is attached to a table or desk. Should the loop be cut, the alarm is sounded. [Hobby Corner Circuit by Dave Johnson]
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. …. [Hobby Corner Circuit by Dave Johnson]

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

SCR Based Burglar Alarm - (electronic design added 6/07)

Security Alarm - (electronic circuit added 1/03)

Security Loop Alarm - A wire is looped through various objects which are to be monitored. The loop wire is typically an aircraft cable but could also be any insulated stranded wire. The loop is attached to a table or desk. Should the loop be cut, the alarm is sounded. [Hobby Corner Circuit by Dave Johnson]

Seismic Alarm - My original "Deer Repellent/ Seismic Sensor" recommended using a speaker with a weight glued to the cone as a vibration sensor (see bottom of page) but it recently occurred to me that the speaker could supply the mass itself. By gluing a standoff to the center of the cone,.... (electronic design added (6/07)

Shed / Garage Alarm Circuit - 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. [Circuit designed by Ron J]

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)

Simple Alarm System - (diagram added 6/03)

Simple blown-fuse indicator sounds an alarm - 10-Jul-08 Issue of EDN A simple blown-fuse-indicator circuit sounds a buzzer and flashes an LED when a fuse blows.... [Design Idea by Vladimir Oleynik, Moscow, Russia]

Simple Door Alarm Circuit - This is a simple, easy to build, alarm circuit. For power, I used a small 9-volt battery. But the circuit itself will work from 5 to 15-volts, just choose a buzzer that's suitable for the voltage....(added 05/07)

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)

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. …. [Hobby Corner Circuit by Dave Johnson]

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)

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)

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)

Single Zone Alarm (Ron J) - A single zone alarm circuit with entry and exit delay and other facilities. (diagram added 6/03)

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,....PDF has many circuits, scroll to find this one.... [Design Idea by Maxwell Strange, Fulton,MD]

Siren Simulator - This siren circuit simulates police, fire or other emergency sirens that produce an up and down wail. (added 10/05)

Snore Alarm (Andy Collinson) - The idea behind this snore alarm, is just to rouse the snorer, not the entire household. To wake the sleeper, vibration is used, not an audible alert. The vibration is provided by a small motor housed in a small 35mm film case, which can be placed under the sleepers mattress or pillow. This circuit has a level control and peak display indicator, a variable trigger....(added 10/05)

Snore Alarm Electronic Device - (electronic circuit added 7/03)

Speed Limit Alarm - (circuit added 9/04)

Speed-limit Alert - Wireless portable unit. Adaptable with most internal combustion engine vehicles. (electronic circuit added 06/07/08)

Sun - Up Alarm - The Sun - Up Alarm can be used to provide a audible alarm for when the sun comes up or it can be used in a dark area and detect when a light comes on. It can also be used to detect a light beam, headlights etc. The circuit works as follows. The phototransistor is very sensitive to light. (Any phototransistor will work fine)...

Sun-Up Alarm - The Sun-Up Alarm can be used to provide a audible alarm for when the sun comes up or it can be used in a dark area and detect when a light comes on. It can also be used to detect a light beam, headlights etc. The circuit works as follows. The phototransistor is very sensitive to light. (Any phototransistor will work fine)... [Randy Linscott]

Alarms: #-C D-G H-O P-R S T-U V-Z