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PIC16F84 Alarm Clock - This is an alarm clock I built. It was very effective
during the sort time I used it, because I programmed it to play a very annoying tune
through a speaker. I actualy started to wake up before the alarm went of, so other
people int he house didn't wake up from the anoying pitches it played. The Jal
sourcecode is available on my download page Features * Timekeeping ….(circuit design
added 11/08) |
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PIR Motion Detector - (diagram added 6/03) |
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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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Power line outage flashes red alert - 06/13/02 EDN-Design Ideas: This Design Idea
expands on a circuit in a previous one to configure a power-outage detector with a
flashing alarm (Figure 1, Reference 1). The circuit plugs into a mains outlet and uses
trickle-charged nickel-cadmium batteries. The green-LED monitors the.....(design idea
added 0/06/06) |
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Power Supply Failure Alarm - This circuit.... (added 10/05) |
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Power-Supply Failure Alarm - (electronic Circuit / Schematic added 10/04) |
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Precision Receiver Battery Low Voltage
Alarm - ….(design added 08/08) |
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Proximity Alarm #2 - (electronic circuit added 4/05) |
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Pump Motor Monitor - This circuit can turn on a light or sound a beeper, whenever
an AC line powered pump motor turns on. It is designed to detect the motor
current using a small inductor placed on the outside of the motor’s power cable.
No direct wire contact is needed. ….(designed by David A. Johnson) |
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R/C Emergency Locator Alarm - (electronic circuit added 4/05) |
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Radio Wave Alarm - This simple circuit is sure to have the police beating a path
to your door, however, it has the added advantage of alerting you to their presence
even before their footsteps fall on the doormat. The circuit transmits on Medium Wave
(this is the small problem with the police). IC1a, together with a sensor (try a 20cm
x 20cm sheet of tin foil) oscillates....(diagram added 6/03) |
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Rain Alarm - This circuit gives out an alarm when its sensor is wetted by water.
A 555 astable multivibrator is used here which gives a tone of about 1kHz upon
detecting water. The sensor when wetted by water completes the circuit and makes
the 555 oscillate at about 1kHz.….(design added 03/08) |
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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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Receiver Battery Low Voltage Alarm -
….(design added 08/08) |
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Red Alert Alarm, #1 - The circuit above provides a 'pulse-tone', like the one you
know from the old Star Trek. The output stage contains a power-booster with Q1
(2N3055), providing several watts to the loudspeaker SPKR1. Clamping diodes are used
to limit the speaker's inductive kickback to a safe level. To prevent the output
signal from feeding back into the 555's via the supply line, the supply lines are
filtered by a capacitor and an isolating diode (C5 and D2)....(Tony van Roon's
schematic / circuit added 08/09) |
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Red Alert Alarm, #2"Red Alert" 555 Siren (Tony van Roon's circuit design added
08/09) |
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Red Alert Star Trek Alarm - Scroll down to locate this circuit. The third circuit
simulates the "Red Alert" siren from the TV show Star Trek. It uses two 555 timers in
the circuit. The 555 on the right is wired as an alarm tone generator and the second
555 timer on the left is wired as a 1.5 second non-symmetrical....(electronic design
added 6/07) |
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Refrigerator Door Alarm - Do your kids leave the door to the refrigerator open? Or
does your celery reach out to keep the door from closing properly when you turn your
back? Here's a simple circuit that beeps whenever the door is open for an extended
period of time (which will also put a little pressure on the fridge loiterers in the
house)....(added 05/05/05) |
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Refrigerator Pig Schematic - Upon opening your fridge door the photocell is
exposed to light and the piggy oinks. (added 2/05) |
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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 Alarm - (diagram added 6/03) |
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RF Transmitter for PIR Sensors - (diagram added 6/03) |
