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DiscoverCircuits.com  --   Dave's Circuits
Circuits designed by David Johnson, P.E.

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Last Updated on:  06/17/2009 03:30:26 PM

Alarm Circuits

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MICRO POWER OVER-TEMPERATURE ALARM
The circuit is powered for years by a single 3 volt lithium battery. It sounds an alarm when the temperature exceeds a certain point. With some minor changes the circuit could also be configured for an under temperature (freeze) alarm. The circuit uses a cheap but accurate thermistor as the temperature sensor.

Circuit Low Power Over-Temperature Alarm designed by Dave Johnson, P.E. (June 4, 2000)

Alarm Circuits
Master Schematic Category List - David A. Johnson, P.E.
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