Let's make a closely MXT like detector!

[KRinAZ]

That looks reasonable. Often I lay out the preamp for thru-hole, then use an adapter board to plug in an SMT opamp.

Great idea on the adapter board - thx.

Are you using an Hitachi-style alpha-numeric display? Many of those are daylight readable and include a backlight.

I agree - a Hitachi display with (added) ambient sensing backlight (that could be turned off) would certainly work and fit right in with the MXT. Lots of options to choose from, TBD

[Carl-NC]

I'm thinking the TLV9362 opamp (successor to the NE5532) would be a good replacement for the MC33077 and MC33178.

That looks reasonable. Often I lay out the preamp for thru-hole, then use an adapter board to plug in an SMT opamp.

The display (I'm thinking a daylight and low light fully readable) - TBD

Are you using an Hitachi-style alpha-numeric display? Many of those are daylight readable and include a backlight.

[KRinAZ]

A quick note - at times I may be quiet for a day or three as I have some other projects going on also, work on this project is still going along.

I'm going to start on a KiCAD schematic, starting at the PS section...and don't plan to worry about the Bluetooth or display sections until the main schematic is completed.

And, all my PIC stuff is supposed to arrive by this Sat 4/25 - those old programmers, a K150, a batch of ten PIC16C76's to torture and experiment on haha, and such...

Onward thru the fog...

[KRinAZ]

Opamps are not a problem, lots to choose from even in thru-hole.

I'm thinking the TLV9362 opamp (successor to the NE5532) would be a good replacement for the MC33077 and MC33178.

Anyone think otherwise, or suggest a more suitable replacement?



The only other component questions (that I'm currently aware of) are:

The specific STM32 - I'm thinking one of the H7's - TBD

A bluetooth module - TBD

The display (I'm thinking a daylight and low light fully readable) - TBD

[KRinAZ]

Ok just a quik note - I think I'm willing to give SMD - for chip devices - a go.

I found a youtube with a guy using soldering tools very much like mine, soldering STM32's and such on his bench, I think I can pick up his method / skill. Still thinking thru-hole for resistors, capacitors, (passives), and diodes, and maybe transistors (just because I and probably you - already have tons of them), and SMD for all chips (with pads that make it easy to check for pin continuity and for bridges) - I may have to make the KiCAD pad footprints - that's ok with me.

[Hristo]

The MXT runs at 13.8kHz in all modes.
The GMT runs at 48kHz.

Yes, you could design a system to use radically different frequencies for different modes; say,

Relic = 2kHz,
Coin = 13kHz, and
Gold = 48kHz.

But the MXT (and GMT) uses a boosted series LC resonance transmitter (L4, C18, C20, and the TX coil) that can only run at one frequency, so \

you'll need to do something different.

like old Bulgarian Golden Mask 5 (like Mambo No.5 song of Lou Bega)

[Okelm]

Get STM32CubeIDE for programming. Get STM32CubeMX for assigning pins and generating start-up code. Both free. Chinese clone ST-Link programmers can be found on eBay for $3. Or, buy an STM32-Nucleo board with the micro you want to use and it comes with an ST-Link programmer that also works independently. That's what I use.

The MXT runs at 13.8kHz in all modes. The GMT runs at 48kHz. Yes, you could design a system to use radically different frequencies for different modes; say, Relic = 2kHz, Coin = 13kHz, and Gold = 48kHz. But the MXT (and GMT) uses a boosted resonance transmitter (L4, C18, C20, and the TX coil) that can only run at one frequency, so you'll need to do something different.

[Carl-NC]

Opamps are not a problem, lots to choose from even in thru-hole.

[KRinAZ]

...My good soldering iron is a Metcal MXPS-5200...

Hmmm...I'll have to watch for a deal on a Metcal MXPS-5200...

[KRinAZ]

...In the MXT the biggest problem chips will be the micro and the ADC, and maybe any switching regulators. A Nucleo board solves the micro but it can be big. You can usually find eval boards for ADCs but they are often not all that friendly for incorporating into a design and are often expensive. So, most likely, you will be stuck with an SMT ADC. Same with switching regs, but fortunately it's easy to find one in 5- or 6-pin SMT that's easy to solder.

Another potential solution is to have the board house install the difficult parts. I've ordered fully built boards from JLC; their minimum order is 2 and their part pricing is quite good...

Something I have in the back of my mind also. If SMT can't be avoided, this would be an option for folks like me, and there are certainly those of you who would be quite comfortable soldering the SMT components.

But first I'm going to explore thru-hole possibilities...more soon...probably tomorrow...