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Hello All. I just found this forum and it seems to be my type of forum. I have an electrical engineering background and I love metal detecting. My first metal detector was a Radio Shack Discovery 2000 (same as Bounty Hunter Lonestar). I received it over 8 years ago. I recently got it out of storage and to my surprise it fired right up, however it doesn't seem to be able to identify any metal targets. I am a pretty good troubleshooter and got down to work. This is a VLF/IB metal detector and I have been unable to find a schematic as of yet so the troubleshooting is going slow. I have been able to verify that I am getting a signal back from the coil and out of the pre amp. The preamp output is connected to pin 1 of a CD4016AE (CMOS Quad Bilateral Switch) via a 50k ohm resistor. Pin 13 is the control for the switch which is a square wave in sync with the local oscillator. I believe this bilateral switch is used to phase demodulate the incoming signal from the coil? However on pin 2 of this IC (output) I do not get an output when metal is passed in front of the coil. I have a very large signal out of the preamp (~10 Vpp) however after passing through the 50k ohm resistor the signal is droped to ~100's of mV which is not high enough to turn on the switch. If I bypass the 50kohm there is an output at pin 2 of the CD4016AE and the metal detector will alarm (although not always right). Can anyone point me in the right direction or have any schematics they could share with me to get this metal detector back up and running? I would upload datasheets and pictures but since I am new I can not attach anything.
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Sounds like the bilateral switch is pfft. That can happen! You can probably buy one at RS for about $1.50, or they may only carry the CD4066 which should also work.
(CD4016 is much cheaper at Digikey or Mouser, although you have to contend with shipping and possibly a small penalty if a minimum order $ is not met.)
By the way, you're not new any more since you have made one post already.
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...and now that you have posted once you can attach pictures and documents.Comment
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