Delta Pulse

[Dean Sarelius]

Hi All,
This is my first post..!
I am interested in building a reliable PI..! I have already experimented in the past with the old Carl Moreland and Mark Stuart designs and I found these easy to build and use but not very stable. I am looking at the new schematic from kt315 and this looks very different to the older designs. I am very familiar with the pulse timing of the old designs but I do not have any understanding with the new circuits and was hoping that perhaps someone could post a timing diagram for the 4066 switches referring to the new circuit the relationship between T2, T4 and T5 pulses and their pulse widths..?
Cheers,
Dean

[Qiaozhi]

Hi All,
This is my first post..!
I am interested in building a reliable PI..! I have already experimented in the past with the old Carl Moreland and Mark Stuart designs and I found these easy to build and use but not very stable. I am looking at the new schematic from kt315 and this looks very different to the older designs. I am very familiar with the pulse timing of the old designs but I do not have any understanding with the new circuits and was hoping that perhaps someone could post a timing diagram for the 4066 switches referring to the new circuit the relationship between T2, T4 and T5 pulses and their pulse widths..?
Cheers,
Dean

Have you looked at the Minipulse Plus design?
http://www.geotech1.com/forums/showt...lse-Plus-REV-B

[Dean Sarelius]

Hi Qiaozhi,
Thank you for providing the design by George Overton..!
Now I am more confused which design I should prefer to use the front end from George Overton or the front end from Delta Pulse..?
Can you tell me which one is the best performing which will deliver the best performance.

Front End A versus B .pdfFront End A versus B .pdf

[Qiaozhi]

Hi Qiaozhi,
Thank you for providing the design by George Overton..!
Now I am more confused which design I should prefer to use the front end from George Overton or the front end from Delta Pulse..?
Can you tell me which one is the best performing which will deliver the best performance.

I have not constructed the Delta Pulse, so I cannot comment from first-hand experience. However, it appears that the DP uses a single-stage pre-amp, and (as far as I'm aware) the DP is designed for use primarily with large search frames that can be used to search for large buried targets. Perhaps KT315 can confirm or deny this?

On the other hand, the Minipulse Plus is designed for smaller coils, and has a self-adjusting threshold (SAT) which means that you must keep the coil in motion. It also has a 2-stage pre-amp that will allow the use of faster coils, and therefore much smaller targets (such as gold nuggets) can be detected. So when you ask: "Which will deliver the best performance?", the answer is: "What do you mean by best performance?". If you're looking for a buried army tank, or for meteorites, then the DP would be best. If you're looking for gold nuggets, or small coins and artefacts, then go for the MPP.

By the way, Q and GO are the same person.

[kt315]

I can find tonns of video in which DP used for coins' hunting. no big problem to re-tune DP for coins or gold nuggets (C4 C5 ---> 1nF, R7 ---> 10k). DP has one-stage preamp working in SAT mode - this done for increase of all stability of the schematic. Minipulse, Surf PI, Baraccuda PI have not PULSE WIDTH tuning, ie you can not simply increase
the TX power in them (related directly with the depth).

[Qiaozhi]

I can find tonns of video in which DP used for coins' hunting. no big problem to re-tune DP for coins or gold nuggets (C4 C5 ---> 1nF, R7 ---> 10k). DP has one-stage preamp working in SAT mode - this done for increase of all stability of the schematic. Minipulse, Surf PI, Baraccuda PI have not PULSE WIDTH tuning, ie you can not simply increase
the TX power in them (related directly with the depth).

I don't know what Dean Sarelius is wanting to search for with the detector, but I would be interested in seeing a video of a DP being used to find gold nuggets. There doesn't appear to be anything on youtube.

By the way, the Minipulse Plus has been designed for simplicity of construction, and therefore it doesn't have lots of knobs to adjust, or options that need to be set. However, if someone did want to be able to adjust the pulse width, then this could easily be accommodated by fitting an external pot. Personally I'm hoping that others will modify the design to either add extra features (such as ground balancing) or customize their units to suit their own needs, as it's flexible enough to allow further experimentation. It should even by possible to use large search frames if the TX pulse rate and width are adjusted accordingly (plus the addition of a suitable heatsink on the mosfet). I can think of lots of possibilities.

[6666]

Hi KT315

I see in your latest DP schematic that R9 plus 500K pot is labeled as ground balance.
How well does the ground balance work ?
Thanks.

[Orbit]

dp pulse does not graund balance Ground balance is done the two channels etc.Look a little more forum !

[Dean Sarelius]

Hi All,
What I am most interested in finding is small gold..! if I can locate even small amounts then I can at least clean up with panning. I already own a VLF machine which is great for the odd coin shooting at the beach but it is totally useless on the gold fields..! I experimented about 10 years ago with the older designs and have been keeping a watch full eye on the progress on the net and the forums and feel that now is a good time to revisit.
My ultimate aim is to develop a PI which can discriminate between ferrous and non ferrous metals and I have already seen that the PI has the capability to do this and I am willing to work through the current designs available now and to experiment later. When I mentioned stable performance what I was trying to say was that I was looking for a design that provided the SAT with good ground cancellation and the MiniPulse clearly solves both of these issues. I am still trying to understand the Delta Pulse circuit but it seems to me that it also provides a SAT just that I can not work out how it compensates for the ground.
I have spent the weekend reading the book "Inside the Metal Detector" by Carl Moreland and George Overton and would highly recommend this book to anyone wishing to develop their own design.
I like the George Overton design because it is easy to experiment between dual and single coil configuration, I understand the circuit and it is simple to set up and use so will try this first.
I would also welcome some more information regarding the operation principles of the Delta Pulse as I like the performance I have seen so far on youtube just that I am finding it difficult to understand the circuit mainly because I do not have any information regarding the T2, T4 and T5 timing so I will consider to put this into Proteus if need be.
For the time being it is my intention to evaluate two or three designs and to eventually convert one of these with MCU and provide some more adjustments by way of a digital encoder and display and to eventually experiment at adding software routines to add discrimination.
Q - Regarding the Minipulse design I note that in the book by CM and GO they recommend to use a 4066 instead of JFET's. Do you think the sampling integrator would benefit by replacing the JFET's with a 4066..?

[kt315]

dp pulse does not graund balance Ground balance is done the two channels etc.Look a little more forum !

bla-bla-bla. and zero of information like always. read the F manuals of DP. look a little more forum YOURSELF.

[Silver Dollar]

Dean if you want to discriminate using PI have a look at the Chance PI.

[kt315]

please read those simple rules for first you only get the board from me.

[kt315]

Dean if you want to discriminate using PI have a look at the Chance PI.

one PI CAN discriminate and you good know that the QED is restricted by minelab trolles here. moderators are not able to save the Project from agression
from the trolles and to ban them in moment. Chance is closed project of Andy, he did return out on VLF design (Quazar).

[kt315]

T2, T4 and T5 timing
---

[Qiaozhi]

Q - Regarding the Minipulse design I note that in the book by CM and GO they recommend to use a 4066 instead of JFET's. Do you think the sampling integrator would benefit by replacing the JFET's with a 4066..?

The Minipulse Plus is a complete working design as it is presented in the REV-B data.
However, it is designed to be simple to build, understand and get working. For those that want to experiment further, then it represents a good platform for that purpose. That have already been lots of questions concerning possible equivalent parts, etc. My reply to these questions is simply this:
Build the Minipulse Plus and get it working as is. Then build a second unit on which you can experiment, and make comparisons with the original board. If you have any success with your various updates and modifications, please post them in the Minipulse Plus thread.

Whether replacing the FETs with analog switches would provide any noticeable performance improvements or not is probably open to debate. Please feel free to try it and report back with the results.