Let's make a closely MXT like detector!

[KRinAZ]

For general purpose bipolar transistors, I use the 3904 (NPN) and 3906 (PNP), either thru-hole (2N) or SMT (MMBT). It's rare in a metal detector that you need more than these.

Oh, ok great, the ubiquitous 3904 and 3906. I guess I was getting too literal about "...I've already mentioned that the resonance-boosted TX circuit should be preserved..." in post 68.

Would you be ok with us just using a 2N3904 for each NPN and a 2N3906 for each PNP - throughout - then?

[KRinAZ]

Just noticed the two 74HC4351's. The 3V logic-compatible part would be 74HCT4351. The 'T' means TTL-compatible which will run on 3V.

Great, will update the components list - which will ultimately will become the BOM.

[KRinAZ]

Are you wanting to do this SMT, thru-hole, or a mixture?...

Short answer: I would choose all thru-hole if possible and use a (thru-hole) Nucleo instead of bare STM32. In the event there is a component that is smd only with no thru-hole alternative then that would be the exception. I think more folks would be able to build this project if smd were at a minimum.

Long answer, I am usually a quick study in picking up new skills, but currently have no experience soldering smd components in place, especially complex ones. I do have a stereo microscope for viewing smd soldering and a probably low end smd soldering station. I have a nice traditional Weller soldering station for thru-hole only. I have practiced unsoldering smd components from junk boards with mixed success. I would need to greatly improve my skills before trying to solder a smd DAC or ADC or MUX or especially the STM32 in place.

Some part numbers are specific to a manufacturer but have generic equivalents. For example, FMMT4403 is the same as MMBT4403 (SMT) and 2N4403 (thru-hole).

Thx, I will widen my search for replacements of not available components.

...Parts that are No Load were not used.

That is good news! and makes sense as it appears the No Load components are often in parallel to components with actual values. I will mark up a copy of my printed schematic that removes all the No Load components.

[Carl-NC]

For general purpose bipolar transistors, I use the 3904 (NPN) and 3906 (PNP), either thru-hole (2N) or SMT (MMBT). It's rare in a metal detector that you need more than these.

[KRinAZ]

On the missing transistors. Search the core number "5087 transistor " then look for surface mount versions. FMMT5087 will be the same as a MMBT5087

https://www.onsemi.com/pdf/datasheet/mmbt5087lt1-d.pdf

The BC849 probably has a common replacement. If you study the datasheet

A search found: "You can replace the BC849 with the 2SC3912, 2SC3913, 2SC3914, 2SC3915, BC847, BC848, BC850, FMMT619, FMMTA05, KST05, MMBTA05or SMBTA05."
I will search on availability of these, then for available ones will compare specs and look for good match.

[Carl-NC]

Pretty much. The 74HCT4053 demod switches will happily run on 3V logic. Where you might need 5V (say, the display) you can use open-collector GPIOs with 5V pull-up resistors. Most STM GPIOs are 5V tolerant.

Just noticed the two 74HC4351's. The 3V logic-compatible part would be 74HCT4351. The 'T' means TTL-compatible which will run on 3V.

[Carl-NC]

Are you wanting to do this SMT, thru-hole, or a mixture? Some part numbers are specific to a manufacturer but have generic equivalents. For example, FMMT4403 is the same as MMBT4403 (SMT) and 2N4403 (thru-hole). Parts that are No Load were not used.

[Altra]

On the missing transistors. Search the core number "5087 transistor " then look for surface mount versions. FMMT5087 will be the same as a MMBT5087

https://www.onsemi.com/pdf/datasheet/mmbt5087lt1-d.pdf

The BC849 probably has a common replacement. If you study the datasheet

[KRinAZ]

OK I made a list of active components (and thermistors) and checked for availability, just a text list (no spreadsheet). Based on a quick (certainly not exhaustive) check (don't shoot the messenger!) we've got some problems to resolve - most of the transistors are not available and, oh no, some are in the transmitter section, critical receiver op amps are not available, and also many components like resistors and capacitors have no indicated value...

U1 LP2951 10ma 30v LDO Voltage Regulator avail Mouser DigiKey
U2 TLE2426 Voltage Reference avail DigiKey
U3 PIC16C76 Microprocessor avail Mouser DigiKey ... hehe, like we totally want to use these
U4 74HCT4053 MUX avail Mouser DigiKey
U5 ADS8320 ADC AVAIL SMT ONLY Mouser DigiKey
U6 74HC4351 MUX avail Mouser
U7 TLC2262 Op Amp avail Mouser DigiKey
U8 LTC1446 DAC avail Mouser DigiKey
U9 TLC555 Timer avail Mouser DigiKey
U10 TLC372 Dual Comparator avail Mouser DigiKey
U11 MC33077 Dual Op Amp NOT avail Mouser DigiKey Obsolete
U12 MC33178 Dual Op Amp AVAIL SMT ONLY Mouser DigiKey
U13 TLC2262 see above
U14 TLC2262 see above
U15 NOT FOUND, DISPLAY POD?

Q1 FMMT5087 Not Available
Q2 FMMT4403 Not Available
Q3 FMMT4403 Not Available
Q4 ZTX749 PNP BJT avail Mouser DigiKey
Q5 2N4401 NPN BJT avail Mouser DigiKey
Q6 FMMT5087 Not Available
Q7 BCB49 Not Available

D1 IN4148 will be available to the end of time, wonder how many billions of these are made each year?...
D2 IN4148
D3 IN4148
D4 N/A
D5 IN4148
D6 N/A
D7 IN4148

TH1 10K NTC avail Mouser DigiKey
TH2 NO LOAD NTC ?

X1 8mhz

Questions:
Potentiometers all linear?
Quite a few components e.g. resistors, capacitors, inductors, thermistor - have no indicated value and instead say No Load - not sure what to make of that?

[KRinAZ]

hereyago :

Kool, many thx, opened just fine. Time to start versioning, I usually just add -V1, -V1a, etc., to the end of the filename...

[moodz]

I see, kool, wonder if claude would be so kind as to gen those diagrams in LibreOffice Draw format? Then they could be edited...and maybe start a KiCAD project from the schematic?...then we'd be on a start toward a PCB...meanwhile...I have some fun tools on order (probably 10 days out)(and a little code to write) and my PIC can't wait to reveal it's secrets

hereyago :

[KRinAZ]

Looks like old school fun. Some of the techniques destroy the original, so it is a one shot deal. Hopefully you will find a nondestructive method. I wish you success.

Yes it does...thanks for that tip - I plan to experiment on some test chips first and get things working, I also hope I have a non- destructive success haha. May take a couple weeks or month but I'll post my results.

[Altra]

Looks like old school fun. Some of the techniques destroy the original, so it is a one shot deal. Hopefully you will find a nondestructive method. I wish you success.

[KRinAZ]

Does anyone know (Carl ) if the PIC's 4 Product ID bytes (for the PIC16C76 would be 0x2000-0x2003) were ever used when programming the PIC? or if any sort of identification information was stored? would be just above program code memory, and perhaps that the code could have referred to?

Also the reserved locations just above program memory (for the PIC16C76 would be 0x2004-0x2006) shouldn't have been used for anything, but were they?

And then the config location (for the PIC16C76 would be 0x2007) certainly should have been set - yes?

Thank you.

[KRinAZ]

Hi KRinAZ, can you tell us what your "fun tools" are? I have an old cnc machine controller that uses a pic18f. The company that made the controller has been out of business for at least 15 years. I would like to build a back up controller if I can dump the hex. Thanks

Hey sure Altra - I can understand wanting to get a backup of that code!

Coming:

First off a Pro2X dock for one of my Dell laptops - so that I have a real 18650 based RS-232 port available.

Second an old PICSTART Plus PIC programmer, and an old PICSTART-16B PIC programmer - both DOS only based, both actual Microchip products, so old they aren't supported in the MPLab IDE (I'm told). I don't have the software (it's DOS software on floppy disk) and don't think I need it, but if anyone has this software I would really like a copy. I still have floppy drives to read the disks if needed. Pretty sure it (the software) won't allow pulling the code, but could be used to program PICs once the binary code is available. But I can use part of the programmers to:




Have:

Third is what's in my head - a very long time ago when I was in the US service (branch undisclosed) we used to (among other things) hack the code from certain military products from less than friendly nations (no further discussions on that will be entertained), and I intend to write some code - and to use part of the PICSTART programmers circuit, and the wonderful ZIF socket they have, to in effect get (or more properly recreate) the code from the PIC.

AI will not be involved here, as I will never allow AI to train on what I have in mind.

But assuming I'm successful I will make sure you know that yours can be backed up also.

EDIT - some CNC machines use controllers very similar to after market (upgrade) 3D printer controllers - as both do similar things - and there is a robust community of Open Source software (Marlin the best/most popular & robust) - where you could very well improve on what you have now - including higher quality stepper drivers, higher resolution code, etc. They usually have a STM32Fxxx or higher micro and aren't code protected - so you can update firmware at will. Watch out for boards with poor quality CN clone mosfets though, and watch out for boards with the very poor CN clone of the STM32 by GD - it would be called something like GDM32Fxxx - no good!

I have two 3D printers and compiled my own code for them, they've been running without a hitch for 3 years now.

You want TMC222x mosfet stepper drivers (the good stuff) not the HR49xx (the bad clone stuff), and the Marlin open source software source (must be configured and compiled) exceeds the capabilities of many of the 3D printer manufacturers - that's why I created my own code from the Marlin sources.

CNC folks run it also...we're off topic now aren't we haha...