Super TGSL With H Bridge TX Diff RX Quad Sampling

[Davor]

I have that in mind, and I'll see to boosting level to the limit, and also I'll try to reduce input impedance.

[Silver Dollar]

That blob is the pad has lifted and is gone now. I had heavy wires for the TX soldered there
and put them on and removed them many times and the pad fell off. I took the board to work
and cleaned it. We have a heated ultrasonic cleaner with flux off in it. It does a good job!

There were flux issues as the board is shipped coated in flux to promote good soldering and
I had cleaned it with alcohol several times but there was still some sticky residue. So I decided
to bring it to work to do a better job. But raising the input level and adding hysteresis was
necessary too.

[Davor]

I'm seeing a blob of something amber-ish right behind the pad a yellow wire in front is soldered in - is it a soldering paste? I hope it is not. That would explain the previous troubles.
I wouldn't expect problems with negative voltage due to the the Tx because its signal does not pass below the ground. Provided there are no excessive loads in a negative rail. I've seen recently a solution for -5V in RS485 using CD4053 (!). It is very minimalistic.

[Silver Dollar]

Well I finished wiring it up today. I'll fire it up tomorrow and see how it works!
I'm a bit worried the minus voltage generator might not like the TX signal as
it is floating a bit off ground. If it doesn't work I'll just throw in a 7660 for the
negative voltage. It only needs a tickle to sync to the TX so should work OK.

[sinclairuser]

Here's a mod schematic (for IDX) I found somewhere. Not sure if they all work but some ideas to try?

[ATTACH]28845[/ATTACH]

thanks all ideas gratefully received.

[Silver Dollar]

Here's a mod schematic (for IDX) I found somewhere. Not sure if they all work but some ideas to try?

[sinclairuser]

Looking through the Archives I found this schematic. That might be the TX tweak for IDX;

[ATTACH]28838[/ATTACH]

You adjust it till it touches the rail. That maximizes your TX current and keeps it more stable
(as it has no where to go)...

thanks for that silverdollar, allways on the lookout for idx mods(for my whites original), its a great machine infact i have a kit of parts for the idx so as to future proof it with this i can repair any fault.
barry if you fancy tinkering with the idx, if you dont have one allready i can recommend the vdi unit i know some build the idx without if you have its a great add on you can build it on perf board as well.

[hoadlies]

Looking through the Archives I found this schematic. That might be the TX tweak for IDX;

[ATTACH]28838[/ATTACH]

You adjust it till it touches the rail. That maximizes your TX current and keeps it more stable
(as it has no where to go)...

THANKS A lot GUYS,,, I will investigate that issue ,CHEERS BARRY..

[Silver Dollar]

Looking through the Archives I found this schematic. That might be the TX tweak for IDX;



You adjust it till it touches the rail. That maximizes your TX current and keeps it more stable
(as it has no where to go)...

[Davor]

The IDX' oscillator has a fixed emitter degeneration resistor of a PNP transistor. It is a handy place to regulate saturation point of this transistor and consequently Tx signal purity. The only thing missing is a trimmer.
It is OK to leave a fixed resistor if you know the optimum value, and in mass production it requires obtaining transistors with narrow tolerance of beta, something that amateurs will never have.

[hoadlies]

Yeah, I'm Croatian. Many people here also have a vibe for languages.

IDX is a nice device on its own, and other than replacing chips with some better choices there is little you can do to improve it. Say, you could improve Tx by introducing a trimmer to set operation point. And perhaps some tweaks with response time bases. Other than that it would be a complete overhaul.

There are details in VLF that are not tackled properly:
- charge injection from switchers - fixing it would require some serious redo in a mixing stage
- 1/f noise - it may be fixed by a chopper, however, the closest thing to a chopper is an AD convertor
- ferrite phase reference, and a wide range GB as separate channels - with regular detectors difficult soils ring as a machine gun, not because of the bad soil, but because of the iron response phase reversal
- only digitally processing detectors have a 4-quadrant discrimination
- sound quality is generally bad, and also quenched hard to avoid chatters

So there is plenty of room for improvements. Only not easily done on the existing rigs.

HI DAVOR,, Thanks for reply You mention trimmer on TX????to set operation point ??? could you explain please [IDX],..

CHEERS BARRY..

[Davor]

Yeah, I'm Croatian. Many people here also have a vibe for languages.

IDX is a nice device on its own, and other than replacing chips with some better choices there is little you can do to improve it. Say, you could improve Tx by introducing a trimmer to set operation point. And perhaps some tweaks with response time bases. Other than that it would be a complete overhaul.

There are details in VLF that are not tackled properly:
- charge injection from switchers - fixing it would require some serious redo in a mixing stage
- 1/f noise - it may be fixed by a chopper, however, the closest thing to a chopper is an AD convertor
- ferrite phase reference, and a wide range GB as separate channels - with regular detectors difficult soils ring as a machine gun, not because of the bad soil, but because of the iron response phase reversal
- only digitally processing detectors have a 4-quadrant discrimination
- sound quality is generally bad, and also quenched hard to avoid chatters

So there is plenty of room for improvements. Only not easily done on the existing rigs.

[hoadlies]

Copy away! I took many of Davor's designs and incorporated them into a Golden Saber here.
I bought a Tracker IV and it only got 3" of depth so I was looking for MORE! You should be
able to add on to the IDX but have to make sure it still functions as it works a little differently
from the TGSL.

I found some old chips in my junk box the other day, one was a 1024 reticon delay chip. I saw
one on EBAY sold for $85! So here might be gold in my old collection of IC's!

I pushed this project up to 12.5 khz as it was suggested that is a good all around freq. You might
like to go higher for your conditions/targets. I think Davor was contemplating a LF vs VLF machine
at one point, there;s lesss noise up there too!

HI,, S/Dollar thanks for the OK to copy your hard work I appreciate that -Mate..

OK i wish I could help with the technical issues But I am afraid i am not compitant in the theory side of things ,but IF i can help somehow I will ..

As reguards to the frequency is this ''governed by the coil design'' ??? & caps that tune the coils??? or the actual circuit used [ie]TGSL,IDX-- ETC.. to what I have learned so far it seems the Coil inductance & caps .. BUT I see some detectors have 3 odd frequency's that can be switched ,,Maybe to complex for the Diy etc,,,, chips-relays-etc- in the coil-head- etc etc ..I guess as you say a happy medium is better as say your 12.5kz !!!??

ON the delay chip I once years ago bought a delay chip ''bucket-Brigade'' from Tandy's,Iwill check I think its a 1024??] & never used it & still have it in its original pack..
The multi-tap Echo units I built are for the ''shadows sound mainly'' they use a programed FV1 chip on a little daughter board SMD already built [made in USA& it gets attatched to a PIET designed mother board with a couple fets & 3x 8 pin OPamps ,a 9v reg & 4x pots exturnal its all analog audio & you have a great Echo unit [Better than you can Buy any where]!!!!..with 8 programs to choose !!!total board size is aprox 4x4'' need's a 12v plug pack only..
,I cannot program chips [The language etc is beyond me] But I was involved in a program with a Dutch Guru & ''PIET'' If you are into guitar etc I can give the details to get hold of a Kit from the Netherlands, the unit is cheap & fantastic ,The unit was 3-4 years in the setting-up which I was a first of 6 guys that were sent the hex files to load into the chip,using a programmer. [PIC-IT] & give reports to the developer [Great Guy PIET] he did all this work for parts only cost for the guitar DIY fellows ..
The Kit comes pre-programed now..& you can buy the programed daughter board from the US & could build the rest from schematic I have all that here ..if interested ..I can email pics-etc etc..daughter board is attatched [piggy-back] by a 14 pin socket ..
I also have a great Tape echo unit Multi-Tap which I converted to All valve operation & head timings copied from the Famous Italian MEAZZI MULTI-TAP Analog Machine..bUT this above unit gives the same results ,,Etap2.. Thats its Title..

BUT I have now changed hobbies for this DIY M/D machines to have a go on the ground !!!.FIND those tin cans of gold Coins HA.Haaar.. [not likely but I will have some Fun]..

GOODONYA-MATE Take it Easy,,,,,,,,,,BARRY..[PS I will send a PM & give my Email address if thats OK] if not NO-WORRIES..]

[dfbowers]

Nice job guys. I have been following this thread from the beginning with interest.
Don.

[Silver Dollar]

Copy away! I took many of Davor's designs and incorporated them into a Golden Saber here.
I bought a Tracker IV and it only got 3" of depth so I was looking for MORE! You should be
able to add on to the IDX but have to make sure it still functions as it works a little differently
from the TGSL.

I found some old chips in my junk box the other day, one was a 1024 reticon delay chip. I saw
one on EBAY sold for $85! So here might be gold in my old collection of IC's!

I pushed this project up to 12.5 khz as it was suggested that is a good all around freq. You might
like to go higher for your conditions/targets. I think Davor was contemplating a LF vs VLF machine
at one point, there;s lesss noise up there too!