Category: Basic Electronic Projects

What is Lie Detector Circuit? The instrument used to find whether a person is speaking the truth or not is called a lie detector or polygraph. It records the heartbeats, blood pressure, and body temperature, and tension level of the person undergoing the detector test. General questions along with other relevant questions are asked to the subject. When the person tries to speak lies, his body physiology changes. These changes are recorded and compared with the results that are obtained for normal questions. Such sophisticated instruments can however give wrong…

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The telephone spy circuit published here is used to hear telephone conversations remotely or to amplify the telephone conversations and also transmits the speech signals in the MW range so that one can listen to a telephonic conversation on a radio set. The device picks up telephone conversations remotely if the telephone set is in the range of a few meters to some tens of meters, the device then amplifies the received signal and plays it through the speaker, and also transmits the signal as a Medium Wave signal. The…

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