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Wailing Alarm - This circuit provides a warbling sound to any alarm circuit.
IC2 is wired as a low frequency astable with a cycle period of about 6 seconds. The
slowly varying ramp waveform at C1 is fed to PNP emitter follower Q1, and is then used
to frequency modulate alarm generator IC1 via R6. IC1 has a natural center frequency
of about 800Hz. [Tony van Roon's circuit] |
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Warble Alarm - The circuit above provides a 'warble' alarm-call generator
that simulates the european 'dee-dah-dee-dah' type sirens used in several european
countries.…. [Tony van Roon's circuit] |
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Water Activated Alarm - The circuit uses a 555 timer wired as an astable
oscillator and powered by the emitter current of the BC109C. Under dry conditions, the
transistor will have no bias current and be fully off. However as the probes get wet
the transistor will conduct and sounding the alarm. An On/Off switch is provided and
remember to use a non-reactive metal.... [from Andy Collison's website] |
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Water Alarm - The LM1830 fluid detector IC from National Semiconductor is
designed to be able to detect the presence of fluids using a probe. This chip requires
a relatively high supply voltage and is not the most frugal power consumer. It is also
quite specialised so unless you are buying in bulk the one-off price is not
cheap.….must register on this site... [Published in Elecktor July/August 2010] |
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Water Level Alarm - A circuit that offers visual indication of fluid level
in a vessel, with a switchable audible alarm. Example uses would be to monitor the
level of water in a bath or cold storage tank.… [Andy Collison's website] |
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Water Level Indicator with alarm - This circuit not only indicates the
amount of water present in the overhead tank but also gives an alarm when the tank is
full. The circuit uses the widely available CD4066, bilateral switch CMOS IC to
indicate the water level through LEDs. When the water is empty the wires in the tank
are open circuited and the 180K resistors pulls the switch....[Radioland.nt.au] |
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Water Seepage Alarm - This simple circuit sounds a beeper when its
electrodes detect water. It is powered by a single 1.5v N cell. A small 1.5v button
battery will also work. …. [Designed by David A. Johnson] |
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Water-level Alert - Beeper or flashing LED alert. (electronic design
added 6/07) |
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Whooper Alarm, #1 - If you've ever watched any TV at all and seen those old
WWII navy movies, you've heard that distinctive "whoop-whoop-whoop" as a destroyer
sliced through the waves, guns blazing, and everybody yelling "battle stations!"....
[Tony van Roon's circuit] |
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Whooper Alarm, #2 - Destroyer Whooper alarm using 5 transistors…. [Tony van
Roon's circuit] |
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Wire Loop Alarm - This circuit is a simple wire loop alarm that can be used
in doorways, hallways, or any other place the tripwire will be broken by intruders.
The circuit has a built in siren, but it can be replaced by a relay to drive an
external siren, commercial alarm, etc.... [Circuit designed by Aaron Cook] |
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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. [Designed
by David A. Johnson] |
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Wireless Alarm - Making yourself an alarm is both useful and interesting:
but the best part is when you take the remote control out of your pocket, and switch
on the alarm while saying to your friends: "I've done it in a weekend". Making
yourself an alarm gives you maximum flexibility: as this project works according to
the Nutchip truth table, you can change it to suit your needs. Some people would like
to have like a "panic" button, in order to sound the siren. Some other pepople need a
very long time to leave the house. Or you might be looking for an alarm that keeps
that special sensor on even if you are at home. Possibilites are unlimited!....(added
05/06) |
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Wireless Alarm Transmitter and Receiver - Here are two circuits that make it
possible to add up to eight detectors to an existing alarm system without running a
single cable. Each transmitter has a unique number that is reported to the central
unit in the event of an alarm, and the transmitter battery condition is monitored.
….must register on this site... [Published in Elecktor July/August 2010] |
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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....(Circuit design added
08/08/08) |
