Beginner would like to build Sandbanks PI Metal Detector

Xavier, here is the coil redone the way you said.

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http://www.thunting.com/smf/index.php/topic,10321.msg68574.html#msg68574

I just tried it Xavier, but its still doing the same thing. I can adjust the volume of the High Pitch sound with the Volume knob, but the Sensitivity knob does nothing to the sound , if I turn it all the way left, the sound is still the same. I turn it all the way right and the sound stays the same.
 I have the coil positioned on a plastic table 46 cm off the floor with no metal around it.
Aliman

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http://www.thunting.com/smf/index.php/topic,10321.msg68584.html#msg68584

OK, here's the pic of the coil connection. The Gray wire is the coil wires going to the Coaxial connection. There's a good connection there, only 2.2 ohms to the Coil.
 I did a few checks of my own, I tested the Output of IC2, -5v Voltage regulator. It was only
 -2v which should be -5v. I tested TR2, it was OK. I also tested the output of IC8, a +12v Voltage regulator and it's output was only  -0.3v.

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No not good are you sure that you set your volt meter to the correct V ? DC and not AC   2) were you on the right scale? 12 or 20 volt is there a transformer on the board? are you using two 9V batteries? can you post a top view of the board so that we can have a look at it perhaps you have your batteries wired up wrong. If I can see the board I will be able to tell you where to measure the voltages or see where the fault is. Lets face it you don?t know much a bout this stuff and I don?t really trust the measurements that you took as it is you had the coil tied up with copper wire and that will never work so lets go through all of this one step at a time together and I?m sure that we will be able to get you going soon OK . now tell me the number on the voltage regulators so that I can see what it?s output voltage is and so that I can tell you where to measure them. I also want to see all of your connections coil, board, head phone, batteries and what ever ells you soldered (close up too).

Best regards
Xavier


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Why regulate the positive of the 12V and the neg on the 5V? (just a question)

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http://www.thunting.com/smf/index.php/topic,10321.msg68630.html#msg68630