Whites Surf PI schematic

[WM6]

What is a good circuit?

Good circuit is those, by which you found treasure. All others circuits are crap.

[yhl]

The metal detectors, can only apply it on the beach?
Can be in the land use?
Sensitive to the nail. Everywhere barking. Treasure Hunt is very difficult
What is a good circuit?

[WM6]

surf pi/ must be a treasure hunt on the beach in it? Distinguish between gold and iron, how to listen to the sound?

It is not possible to distinguish between Ferro and non-Ferro targets with this detector.

[yhl]

I want to know.

surf pi/ must be a treasure hunt on the beach in it? Distinguish between gold and iron, how to listen to the sound?

[TH Jim]

The sample timings look OK, the first sample window can be seen to cover the delay curve in the bottom right scope capture.

If anyone decides to use my SurfPI board and schematic that Silverdog has posted above then please be aware that it may contain errors. Also it must not be used for commercial gain without permission, it is copyrighted to me. I was hoping to tidy it up a bit before releasing it on the forum.

Regards, James.

[silverdog]

I have built the circuit using Oxygen's layout, and have watched out for the common pitfalls (like inserting that specific transistor reversed), so I have a degree of confidence that it should work. However, it does not. I checked it with a scope, but could not find any obvious errors (although I am far from understanding how it should work).
On the following shots, channel 2 is always showing the 5534's output (pin 6), while channel 1 is showing various spots.

4066, pin 2 (signal after the sampler switch)


LM358, pin 5, 6, 7:


LM358, pin 2 (threshold input):


4066, pin 5 (2nd sample control signal) and pin 13 (1st sample control signal):


When I close on a piece of metal, nothing visible happens after the 1st OPA (integrator, after the sampler). I find suspicious that its output is so small... I would have expected a larger signal there.
Does anyone have any advice where I should be looking?

Many thanks.

Have a look on page 2 of this thread, ApBerg shows some scope pics for delay settings, if you sampling at the wrong time you won't detect anything

http://www.geotech1.com/forums/showthread.php?t=17240

[TH Jim]

SFThomas:

I have not built the Oxygen board, there were some comments earlier in this thread that it contained errors, although i have not checked it myself, but your waveforms look good. Transmitter and gating pulses look OK. You should be able to see the change in the decay curve on the output of the NE5534 when placing a large target near the coil.

Reagrds, James.

[satdaveuk]

Thanks

Thanks Silverdog your a diamond, also thanks for your time Bernte
Regards

[bernte_one]

thx silverdog

[silverdog]

Single sided surf is what im after Bernte
thank you

I have this single sided version from James Owen, I was going to get some boards made but other projects took over !
Q6 silkcreen is wrong, rotate the mpsa13 when inserting

Silverdog

[satdaveuk]

say exact what you want maybe i can help than
surf pi singlesided pcb ( search for oxygen layout)
or double sided pcb?

or another project

Single sided surf is what im after Bernte
thank you

[bernte_one]

So if anyone here would be so kind to upload the PCB,layout, and a very recent circuit diagram i would be greatful.
Dave

say exact what you want maybe i can help than
surf pi singlesided pcb ( search for oxygen layout)
or double sided pcb?

or another project

[satdaveuk]

No MPSA14, how substitution?
I only BC548 how Darlington?

I got quite a few of the MPSA14 in stock they were cheap, if you want one or two drop me a line with your address and i will post them to you.
Regards

[satdaveuk]

Have you looked here? -> http://www.silverdog.co.uk/shop/

yes and at somepoint i will do business with him, prpberly the chance pi when there available on the other hand i do like to make my own pcbs etc and this particular project I have quite alots of the components in stock and it appears quite stright forward after watching everyone else iron out the bugs.
God i sound so selfish, but im not really.
So if anyone here would be so kind to upload the PCB,layout, and a very recent circuit diagram i would be greatful.
I have never made a PI detector before so this is my first.
Many thanks in advance
Dave

[sfthomas]

Surfmaster not working

I have built the circuit using Oxygen's layout, and have watched out for the common pitfalls (like inserting that specific transistor reversed), so I have a degree of confidence that it should work. However, it does not. I checked it with a scope, but could not find any obvious errors (although I am far from understanding how it should work).
On the following shots, channel 2 is always showing the 5534's output (pin 6), while channel 1 is showing various spots.

4066, pin 2 (signal after the sampler switch)


LM358, pin 5, 6, 7:


LM358, pin 2 (threshold input):


4066, pin 5 (2nd sample control signal) and pin 13 (1st sample control signal):


When I close on a piece of metal, nothing visible happens after the 1st OPA (integrator, after the sampler). I find suspicious that its output is so small... I would have expected a larger signal there.
Does anyone have any advice where I should be looking?

Many thanks.