Making a Simple Metal Detector
Metal detectors have two oscillators. One is tunable and the other is "Fix" with a loop. Both are "Tuned" at same frequency. Outputs from this two oscillators are then mixed in a mixer which produces only the difference. Means, if both oscillators are at the same frequency, there is nothing heard in the speaker.
To start with, you need to "Zero beat" both oscillators or say "Null" them while keeping your detector in the free air, away from metal objects. Use the tuning control provided for this purpose.
Once this is done, start placing detector around metal objects and you will notice that "Zero beating" is getting disturbed and an audio tone from the speaker is heard. Wow, the detector has found a metal and its working!! Authorized by Nina Gajjar
