AGD25.1 PI Detector Development Work

[ivconic]

...If you depend on videos to make decisions you are different then me...

No, of course not. Video however good and true; is the least important factor in deciding whether to start doing something or not.
William Lahr didn't make a single video, he redrew the schematics by hand, often sloppily... and yet I made most of what he drew so far.
I am asking to see the video for other reasons.
I explained most of the reasons in the previous post.
English is not my native language, I often don't write and express myself properly, I guess that's why you didn't understand almost anything of what I wrote in that post.
You already had one (or maybe a couple, I stopped following) topic on the forum. A very large and comprehensive topic. Look back how many people joined and participated in that topic?
And then find a topic on the forum like... let's say Delta Pulse. Look at the number of pages and the number of people who participated in that topic.
Do you get the point?
The forum is not a place for rather autistic actions (even in your case when you post good and interesting things). A forum is a place where people gather and discuss together.
A forum is a place of interaction. Cooperation. Give and take place it is.
Let me repeat this, maybe this time it will be clear to you?
A short video of your magnificent work in action in a room, on targets such as a coin, a piece of iron, a piece of aluminum foil... will that take up too much of your time? Will it cost you too much? Will it kill you?
No, it won't. It will take you 10 minutes at most. And that recording will tell us a lot.
The autism you insist on is very foreign to me.
Have it your way.
You wrote "tons and tons" of posts, "tons and tons" of claims.
You haven't given even 1 second of footage showing how your great work works in practice.
I'm sure 90% of the forum members agree with me.
But they are too cultured and don't want to stir up dust, but just watch quietly from the sidelines.
As for circuit analysis... as you say; I'll just say this: ha, ha, ha!
The works on this forum are the best proof that very often what works perfectly on paper; in practice it often produces clouds of white smoke... if not then in the mildest form it doesn't work at all.
The forum is full of years wasted on "phenomenal" ideas and "solutions".
Not to mention wasted money.
Okay, life isn't fair. Some of us can waste money and time like that and enjoy it. Unfortunately, some of us are not in that position.
Ok, this is my last post on any of your topics. What did we find in the end?
We discovered that 10 seconds of video will drastically jeopardize your precious time, health and financial condition.
So I won't insist on it anymore. Enjoy!

[dbanner]

I wouldn't describe the reverse engineered schematics drawn by William Lahr as "sloppy", far from it, they are very, very good, considering they were drawn by hand. And they are extremely accurate, except for a few errors here and there spread across several dozen or so schematic drawings attributed to him.

As far as demo videos go, I agree those would be nice to see. But I'm very satisfied just to follow the evolution of his work.

Besides, shooting videos takes up valuable time, which is just a distraction when engaged in high level cerebral work.

[Auto-Mation-Assist]

Today I finalized the new circuit boards for mounting the parts that will be on the front and rear panels.

The power connector and its associated on/off switch are separate and do not connect to the front panel circuit board. Wires are soldered to the in row holes from the front and routed through the black colored holes to the back side of the board shown. These wires will have pugs that route to various locations on the TX or RX boards. I usually use 24 AWG started wires from salvaged stripped 10 conductor cable which supplies 10 standard wire colors. The size of the front panel circuit board is 4 by 2.42 inches. Using this circuit board provides a reasonable attractive was of handing the wires and provides good flexibility to route the wires to the required sockets on the two main circuit boards.

The front panel circuit board:





The rear panel circuit board solders to the standard older five pin GX series connector. And contains all damping resistors and related switch for adding additional damping for a DD coil. This board has several 1 watt trimmers to handle the final damping adjustments. These trimmers are mounted on the other side of the circuit board so that they can be adjusted easily though holes in the back panel. These holes will normally be plugged by properly sized screws. A test point will be available to make adjustments without requiring removing the enclosure. The trimmers are 0.250 inch tall and 0.505 inch round. I decided to eliminate the TX/RX diode I mentioned in a prior post on this circuit board.

The resistors I have chosen to use are quite large due to having higher wattage ratings than those typically used, and are none inductive wire wound types. It is not required to use these types and metal film types can be used as well. Some board space could be saved by using lower wattage resistors like the metal film types that handle part of the final adjustment damping towards the bottom right of the circuit board.There is a slot to hold the ferrite core in the TX path in place so it does not move around once a bit of adhesive is applied.

The TXC solder points handle the TX signal, and the voltage sample for determining a the desired decay point of the coils decay wave form. The RXC connection point has one ground wire and two connections for the receive signal. These all route to the RX board. The rear panel circuit board is 3 X 2.1 inches.



I placed the order for these two simple boards with PcbWay today.

[Auto-Mation-Assist]

I'm slowly progressing of testing the prototype transmit and receive boards I posted pictures of earlier. I did find that the TX board had several footprints that were corrected but linked to wrong parts. I wired around these two problems and corrected these for when I place the order for the final circuit boards. I was able to program the STM32 MPU with no issues and is operating properly. While looking at the circuit board layout for the components of the rear panel circuit board and the direction of the wires that exit the board that these were not optimal and required more length than necessary. The rear panel board is working properly and does allow me to properly adjust the damping of the coil. I have designed a new rear panel circuit board that is slightly smaller and also routes is interconnect wiring to better directions for attaching its plugs to the sockets on the TX and RX circuit boards.

Picture to the new rear panel circuit board.
The 5 pin coil connector will be machined to allow the complete rear panel board to be removed from the actual metal rear panel. I have ordered a 16mm x1 tap and die set for this work and will use our lathe to do the required machining.





Here is a picture of the TX and RX boards plugged together back to back and the normal position that the rear panel circuit board will be in.


As you can see the TX wiring is heading it the wrong direction with the prop type rear panel circuit board.

The switch on the rear panel board selects Mono or DD coil loading. DD has more coil loading based on my tests that show that my DD TX coils have less inductance than my Mono coils. However I'm not sure if that is always the case. I have Carl's Third Edition "Inside the Metal Detector" book but have not looked to see it it mentions the typical inductance differences between the two types of coils and how that affects damping adjustments.

Also if you look at the 5 pin coil connector you can see the stop ring that is normally on the outside its mounted panel that need to be machined down to allow for threading the area underneath it. I added a ground wire to the outer shell of the connector for my prototype testing since there is no actual rear metal panel to provide the ground for the connectors shell.

The new rear panel circuit board has the correct spacing for the connectors pins so that the circuit board mounts more closely to the connector. This will provide a better adjustment range for the switch and connector to the actual rear panel.