Circuit Project Electronic

Uninterruptible Alarm Power Supply using LM7805
Friday, October 31st, 2008

Although this Power Supply was designed for the Modular Burglar Alarm - it has other applications. It provides an output of 12-volts - at a current of up to 1-amp. In the event of a mains failure - the back-up battery takes over immediately. And when mains power is restored - the battery recharges automatically.
The [...]

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Snore Alarm using IC 555
Monday, October 20th, 2008

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 [...]

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Water Level Alarm using IC 4011
Monday, October 20th, 2008

This circuit will trigger with any fluid with a resistance under 900K between the maximum separation distance of the probes. Let me explain further. The circuit uses a 4050B CMOS hex buffer working on a 5 volt supply. All gates are biased off by the 10M resistors connected between ground and buffer input. The “common” [...]

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