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Simple blown fuse indicator sounds an alarm - 07/10/08 - EDN-Design Ideas: A
simple blown-fuse-indicator circuit sounds a buzzer and flashes an LED when a fuse
blows.....(design idea added 009/08) |
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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) |
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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 - (diagram added 6/03) |
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Siren Simulator - This
siren circuit simulates police, fire or other emergency sirens that produce an up and
down wail. (added 10/05) |
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Snore Alarm - 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) |
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Snore Alarm Electronic Device - (electronic circuit added 7/03) |
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Speed Limit Alarm - (circuit added 9/04) |
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Speed-limit Alert - Wireless portable unit. Adaptable with most internal
combustion engine vehicles. (electronic circuit added 06/07/08) |
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Sun-Up Alarm (Randy Linscott) - 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)....(added 09/05) |
