Hybrid metal detector

[eduardo1979]

Hi guys.
I have been thinking about a hybrid metal detector for a long time, but today an idea has come to me and I am not sure if it will work or not. I have mixed the Whites Classic 3 with the Surf PI.
I hope the experts will weigh in on this scheme.
I have made minor modifications to both the Classic 3 and the Surf PI. At the input of the RX preamplifier I have added two diodes in antiparallel to limit the voltage and avoid OP-AMP overloads. In the second sample of the Surf PI I have added a 500K potentiometer to be able to adjust the ground balance. I have eliminated the audio oscillator of the Classic 3 that was made with an IC LM393 and I have taken advantage of the same generator of the Surf PI. I have also added a switch to be able to detect in discrimination mode and all metals mode.
I hope to hear your opinions.
Greetings to all members.

[Qiaozhi]

Hi guys.
I have been thinking about a hybrid metal detector for a long time, but today an idea has come to me and I am not sure if it will work or not. I have mixed the Whites Classic 3 with the Surf PI.
I hope the experts will weigh in on this scheme.
I have made minor modifications to both the Classic 3 and the Surf PI. At the input of the RX preamplifier I have added two diodes in antiparallel to limit the voltage and avoid OP-AMP overloads. In the second sample of the Surf PI I have added a 500K potentiometer to be able to adjust the ground balance. I have eliminated the audio oscillator of the Classic 3 that was made with an IC LM393 and I have taken advantage of the same generator of the Surf PI. I have also added a switch to be able to detect in discrimination mode and all metals mode.
I hope to hear your opinions.
Greetings to all members.

I assume you're aware of this?->
The Voodoo Project - Published October 2020

[eduardo1979]

I bought the book just as it came out on Amazon, but programming is not my strong point. I'm from the old school and I like analog electronics more. I read the book and understood the working principle of your detector. Thanks for answering.

[Carl-NC]

I don't understand how this is supposed to work. You have the RX coil connected to VLF demods that are clocked by a damped PI TX. I don't think this will do what you want, you will need some one-shot pulse circuits in there somewhere. Also, there is no PI side, which would be another preamp connected to the TX coil.

[eduardo1979]

I don't understand how this is supposed to work. You have the RX coil connected to VLF demods that are clocked by a damped PI TX. I don't think this will do what you want, you will need some one-shot pulse circuits in there somewhere. Also, there is no PI side, which would be another preamp connected to the TX coil.

Thank you Carl.

[Qiaozhi]

I don't understand how this is supposed to work. You have the RX coil connected to VLF demods that are clocked by a damped PI TX. I don't think this will do what you want, you will need some one-shot pulse circuits in there somewhere. Also, there is no PI side, which would be another preamp connected to the TX coil.

That's exactly what I was thinking, which is why I asked the question in post #2.

Eduardo - You can achieve the same thing as Voodoo but without software. You just have to replace the processor with some hardware. It does work, as some of the many prototypes I built did not have a processor.

[transistor86]

so this scheme works?