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Sensor circuit diagrams
October 5, 2010
Some 15 years ago it was common to see small key-holders emitting an intermittent beep for a couple of seconds after its owner whistled. These devices contained a special purpose IC and therefore were not... [more]
October 4, 2010
This is basically a Schmitt Trigger circuit which receives input from a cadmium sulfide photo cell and controls a relay that can be used to switch off and on a street lamp at dawn and... [more]
October 4, 2010
Here is a simple thermostat circuit that can be used to control a relay and supply power to a small space heater through the relay contacts. The relay contacts should be rated above the current... [more]
October 4, 2010
This circuit will detect AC line currents of about 250 mA or more without making any electrical connections to the line. Current is detected by passing one of the AC lines through an inductive pickup... [more]
October 4, 2010
The finish line circuit detects the first of three cars to cross the line and illuminates a 25 watt 120 VAC lamp indicating the winning lane. Three photo transistors are used which can be embedded... [more]
October 4, 2010
In this fire alarm circuit, a Thermistor works as the heat sensor. When temperature increases, its resistance decreases, and vice versa. At normal temperature, the resistance of the Thermistor (TH1) is approximately 10 kilo-ohms, which... [more]
circuit from:http://www.extremecircuits.net/2009/07/fire-alarm-using-thermistor.html
October 4, 2010
This circuit, enclosed into a small box, is placed in the fridge near the lamp (if any) or the opening. With the door closed the interior of the fridge is in the dark, the photo... [more]
circuit from:http://www.extremecircuits.net/2009/08/fridge-door-alarm-circuit_21.html
October 4, 2010
The circuit, enclosed in a small box, should be placed in the fridge near the lamp (if any) or close to the opening. With the door closed, the interior of the fridge is in dark,... [more]
circuit from:http://www.extremecircuits.net/2010/01/fridge-door-alarm-schematic-2nd-version.html
October 4, 2010
It beeps if the fridge door is left open for too long or hasn't closed properly, to stop food from spoiling. There are lots of other uses as well. A refrigerator or freezer door that... [more]
October 4, 2010
Whenever AC mains supply fails, this circuit alerts you by sounding an alarm. It also provides a backup light to help you find your way to the torch or the generator key in the dark.... [more]
circuit from:http://www.extremecircuits.net/2010/05/mains-supply-failure-alarm.html
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