Modifying a digital thermometer to beep at specific temp


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I'm trying to make a digital thermometer beep at a specific temp so I don't have to sit and watch it. Any help on how to build a cheap one would be great too. All the thermistors I see advertised have leads that need to be hooked up to a computer. Any ideas on how to wire some Radio Shack parts up to do it myself? Thanks in advance to any electrical engineers or smart poeple!!
Dear all, The basic circuitry would be a voltage comparator driving a small 'beeper'. If the thermistor operating point(resistance at the point of interest) is available then it would be trivial to compare the voltage across the thermistor and a known voltage(for example set up by a potentiometer.) An opamp and a 555 would be sufficient along with a couple of other passive components. But be careful about where this homebrewed circuitry is going to be used. Have fun.

You didn't specify your desired temperature range, But if you go to EXTECH.COM your heart will go pitter-patter. Item # 401012 is good for a range of -58 to 158 F. and sells for a mere $19.00 + S/H. They also carry a multitude of pyrometers and controllers.
Just buy an LM34(Fahrenheit) or LM35(Celcius).
They cost about $2 each. They give an analog
voltage whose value increase with the termperature.
You can then simply use an ordinary op-amp (I prefer the general-purpose 351) to trigger the buzzer.