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Hi Eduardo, will you post the layout of your board?
To build your project. Thank you.
To build your project. Thank you.
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Hello OrbitOriginally posted by Orbit View PostWorks great! But I think some people were still disappointed.. It was thought that it would be equal to Smart Pulse Hybrid or better than it.. Still needs work?!
Which part of the world are you from?Comment
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Before watching the video, a mandatory note:
- Not a single decoupling capacitor was fitted...
- Coil is "random", totally inadequate... 18cm diam.
- The damper resistor is 390 ohms, rather randomly chosen, probably inadequate.
- The frequency is set to 1.1kHz
- Gain is at approximately 75-80%
- Delay is at a minimum.
- Mosfet transistors are 2 x IRF840 and 2 x FQP3P50.
- I also couldn't buy a 74HCT4053 anywhere so I put in a 74HC4053 instead.
The set of opamps was the same as on the original schematic, and then I replaced them with TLC274 and TLC272.
I did not notice any major differences in performance.
I assume that the differences will be noticed only when the device is arranged more neatly
(addition of a decoupling capacitor and a more adequate coil with a damper).
At one point, two very similar ancient Roman coins, the so-called "Antoninian" can be seen;
one has a good patina and the other is "burnt" and without patina.
You will notice that it is the one with better patina and quality; much better detected.
Yes, there is a noticeable "cut" and "chirpy" audio as well as a very quiet "buzz" in the background.
The speaker is 8 ohms.
Ground balance works great! No objections!
Before shooting the video I did a GEB adjustment on the piece of antique brick from the video.
Otherwise, that brick is detected by all detectors when GEB is not performed on it.
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Ok, I'm happy for now. The detector worked from the first, without any problems.
Now to recap...
What would I like to see better on this detector?
1) Much softer audio without the "sharp" sound and without the background quiet "buzz" ... which may not be heard in the video.
2) To improve it so that it detects those coins from the video that it does not currently detect.
The most important thing is that it not detects (but it should) that small silver "Ottoman" coin, which is about 6-8mm in diameter but is very thin and is made of pure silver.
(The Minelab Vanquish 340 detects that coin incredibly deep, noticeably deeper than the Deus 1)Comment
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This type of subtractive GB always results in a target hole and it's possible the Ottoman coin is in this hole. Turn off the GB and see if it can be detected. If so, it is in the hole. You can move the hole around by changing the timing parameters but then something else will end up in the hole. The book describes how to eliminate the hole.Originally posted by ivconic View PostComment
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I just did a test with a 0.5g gold nugget, and it detects it very faintly. The TDI detects this nugget about 10cm in the air. The TDI also has a different GEB circuit. I assume that could also influence the depth.
https://www.youtube.com/watch?v=3jIz7-Rm__IComment
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The GB in this design is done differently than the TDI but the results are the same, except for where the target hole ends up. Any time you have trouble detecting a target turn off the GB and try it.Comment
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The TDI with the GB ON (at number 8 ) detects the nugget at 10 cm. The Bipolar PI with the GB off detects it at 3 cm, and with the GB potentiometer halfway through the range, right where the hot stone is rejected, the nugget is detected at 1 cm. I'm surprised that the TDI, with the GB in any position, doesn't lose depth for the 0.5 g gold nugget, and the Bipolar PI loses depth when changing the GB value. I understand that both detectors have subtractive GB, but in different configurations. I've tried modifying the GB on the Bipolar PI to match the TDI, and it doesn't work. There's no way to reject the stones. I've put a 1 Mohm potentiometer on the GB to get a good adjustment range, and it doesn't work either.
Any ideas, Carl?
I've attached the schematic of my circuit, the one shown in the video, in case it helps anyone.Comment
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Sure will do!Originally posted by Carl-NC View Post
First to find the damn 0805 caps and fit them too.
The new ones I ordered will reach me God knows when.
Then to wind a better coil and to "jig" an adequate damper.
And only then can I approach any serious tuning and testing.
By the way, Carl, one "stupid" question; considering this is an H-Bridge TX... what cable to coil do you recommend I use?
Currently on the video is a coaxial cable, the middle one is PVC coated and braided around it.
In DD configuration and in mono configuration, do you have any special advice?Comment
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Eduardo what is your Tx pulse width?Comment
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Hello Altra.
The pulse width is 50uS and the frequency is 2000Hz.
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I have found with BP you need a Tx pw of greater than 70us to eliminate certain ground. The ground signal at 50uS tx does not have enough power during the the GB sample to cancel the ground signal during the target sample.Originally posted by eduardo1979 View PostComment
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Hello Altra.
Let me explain my problem. The Bipolar PI with its original GB, just as Carl designed it, works perfectly and rejects any hot stones very well. My complaint is that this type of GB, I think, significantly reduces the depth of the detector. I've tried replacing the GB circuit in the Bipolar Pulse with the TDI's GB circuit, and it doesn't work. The TDI's GB detects all hot stones. I don't know what's going on there, because in theory it should work. I've used the TDI's GB in many detectors and it's worked well the first time, but it doesn't work in the Bipolar PI, and I don't know why. I like the TDI's GB because it doesn't reduce the depth of small gold objects like the Bipolar PI's GB does.Comment
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