Gadget Freak Case #112: Simple Pressure Alarm Monitors Water and Air

November 19, 2007

William Grill had a periodic problem with backed-up water in his laundry room. The laundry tub has a shallow drain that is shared with the kitchen plumbing. The drain would regularly get clogged with refuse from kitchen disposal debris or laundry "goop." When the drain clogged, water backed up onto the floor, creating a "rather unpleasant laundry room crises."

Grill considered a water monitor, but he wanted a bit more warning so he could avert flooding. He wanted to know when the drain was getting clogged before "water was all over the place."

He created a sensor that is set for two points - 1 and 5 inches of water in the laundry tub. The sensor sends an alarm before the water crests the tub and splatters all over the floor - all for less than $12 in components.

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Amt Part Description

1 Quad op-amp 735-3649
1 Detector 870-0202
1 100 ohm R Single Turn Pot 754-0840
1 10K ohm R Single Turn Pot 754-0845
1 10K ohm R 1/8W Resistors 296-6224
2 680 ohm R 1/4W Metal Film Resistors 296-0039
2 470K ohm R 1/8W Carbon Resistors 296-6238
2 Diodes 263-1538
1 Regulator 263-0136
1 Power Jack 1.3 mm 932-2202
1 PiezoAlarm 623-2024
1 Black 2.75 x 4.6 Enclosure 278-0571
1 SPST Rt angle Toggle 948-0261
Additional parts required:
1 Sensor
1 Controller
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