TM 808 White's

[ivconic]

A friend retreived White's TM808 to me few days ago.For the first time in
my life i had chance to see and test it properly. I have very positive
experience with it. I already heard in the past that some people claimed
TM808 is not so good as advertised,but now,having my own experience, i can
say; yes it is very good device,working as claimed on White's advertisements.
I guess, the main thing about it is that man should understand how to adjust
it properly. This type of metal detector is quite different than ordinary
IB's,so if you have previous experiences with some IB....well,you better do
not rely on those. The main point is that "reseting" device will limit
depth to range proportional with range were the nearest conductive material
was at the time of "reseting". So if you lift TM 808 high over the ground and
"reset" it, later settle to normal position and fine readjust "Threshold" to
gain no sound or very "mum" sound, than you'll gain maximum depth with it.
Adjusted like that TM808 is very sensitive, and can detect large items over
the 4 meteres deep. When i said "large" i mean item as standard oil barrel
and larger. It is also very useable for detecting cavity,cave,tunnel etc.
I am still planing to do more tests with it, but my main interest is to do
reverse eng. on it and make another one. Since i do have original,it should
not be some problem. It will need some time.I am planing to reassemble unit,
make some draws,unsolder all components,copy pcb,later solder all over again,
assebmle it...and that is all.But! I do not intend to reassemble coils.
No way! Since those are assembled and glued hard,closed in a pipes and it should
be very difficult and risky to open those....
So i was asking is anybody knows any data about coils for TM808 ?
I think KT315 already posted some about TM808. But posted pcb was SMT.I am not
working with SMT cose do not have conditions.Now i have chance to do it on
conventional way. But about coils i do not know any data yet.
Also i do intend to post pcb draw here when prepare it.
Anybody interested to join this subject? Any datas for coils?
regards

[Geo]

Hi Ivconic.
1. About TM808 coils if i remember right Esteban sent a schematic with coil transformers (it is one loop coil). Now i am at work but when i will go home i'll see at PC because maybe to have the coil details.
2. I attach you a pcb file . I can't open it:mad: so i dont know who version is.
3. I asked you about the program that you draw the electronics schematics but you forgot:confused: to answeer
Regards
PS If you open the file tell me about it or with who program you opened it

[Leto]

favorite KT315's formats

PS If you open the file tell me about it or with who program you opened it

Hi Geo... This is Sprint-Layout file (ABACOM)
http://www.abacom-online.de/uk/html/sprint-layout.html

The file you attached is SMT board Ivconic mentoned.
Is there any shematic to go with it??

And for Ivconic - thanx and please keep on.

[Geo]

Hi Geo... The file you attached is SMT board Ivconic mentoned.
Is there any shematic to go with it??

.

Hi Leto.
Yes i have the schematic of TM808 from this forum. I attach it

[Satel]

The PCB done without part of opamp U6 (legs 8,9,10) and without part of U8 (legs 1,2,3 and 5,6,7, (cave balance channel)). U6 changed to MC 33078.

[Geo]

Hi Ivconic. Go to schematics....TM808 Schematics by Anatoliy and read a text from Esteban about coils. You must take wire 0.18mm and turn it around the core until to measure 2.1 Ohm.
Regards

[ivconic]

Sprint.


Sometimes i am using Sprint .... but most of the time Windows Paint and copy&paste....ha,ha,ha...I am to lazy to bug myself with Protel or Pcad or simillar...Sometimes Protel makes his own connections????
About Esteban hints on coils...well...i am not sure at all.
Also i did not understood him well?? On first examination on coils i asume that there are ordinary windings inside,but closed in pipe which role is to form faraday cage.....no transformer or simillar at all. I am a bit confused about Estebans post...? Maybe Esteban should come here and help a bit?
Esteban,can you explain a bit more?
I was thinking anyway to wound some windings and try....i'll see later.First i have to finish pcb..
regards

[Esteban]

I repair a TM808 in last the 80s, the causes of fail was the 3140 IC. This detector is good, but in very wet area (soil and air) produces much falses alarms. In dry terrain is very sensitive. Was in this opportunity I make same meditions in the coil. The sectioned aluminium loop is "reconnected" in a aluminium cilindric mass via 2 aluminium Allen screws, so the loop is closed, as a shortcircuit, no gap. This is the secret of major transference in transmitter and good receptivity in receiver. Here the ubications I remember:

[ivconic]

Many thanks Esteban!


Thank you very much Esteban! THis will clear up a bit my doubts about coils.
I was asuming wrong about those.
About core, do you know dimensions?
Also i was thinking to make ordinary coil with some wire windings? How about that?
One more photo...

[michael]

...i can say; yes it is very good device,working as claimed on White's advertisements.
I guess, the main thing about it is that man should understand how to adjust it properly. This type of metal detector is quite different than ordinary IB's,so if you have previous experiences with some IB....well,you better do
not rely on those....

Ivconic, did you take this detector to somewhere with high mineralization soil or with small holes in ground and see it's behavior?
As you know detection a test metal target buried in ground is not enough for describe as an accurate locator, one metal detector is accurate and precise that gives no signal for anything except to metals. only metals.
Otherwise I have seen Garrets work and have used White's Spectrum XLT they detected every thing and didn't slap hand of everything; all of man made potteries, ceramics, bricks, various soils,.... and at last metal( not deep), then how could rely on their signal for digging?[ Here we name those Everything Detector] what score will you give for TM808 reliability?
another thing; I have heard TF 900 is much better than this so that it has 2 frequency option(12.5 & 73.5 Khz) and with 12.5 it detects metals reliably and gives no signal for every cavity.

[ivconic]

Next step...

So,as planed,first step is finished. I just unsoldered all
components from pcb. To tell you the truth it was "labour".
But,have to say, White's used extra quality materials here.
Tribute to White's. The very best ever prepared pcb i saw
in my life. Holes are metalised,pads,vias superb!
I used my Salomon soldering iron,which is very good and
neither one damage occured! Pcb need some cleaning,so when
done, i intend to scan it on 600dpi.Later, using Corel Photo Paint
i intend to redraw all over photo,do some more cleaning,sharping
and finalizing to make file for offset printing.
I done reverse eng. same way,so many times on much originals
so far, but i have to repeat, this pcb is best quality i ever saw!
For now here is blured photos(my camera is modest).
I'll also post scans when done.
regards
P.S.
Esteban,although you explained pretty good, coils here,please can you
do some extra work. Can you use paint or simillar and draw more
preciselly inner composition of coils.. I didnt get quite clear
picture of those yet.Call me stupid,but i would like to be sure
what is all about.Dont want to make any mistake when making those.
Thanks in advance! Also everybody else, if somebody have pictures
draws&stuff about those coils,please come here and post.



Michael you made good points there! No, i didnt tested it detailed yet.
I intend too in future. But anyway i do have strong wish to make another...and maybe another...and another....ha,ha,ha! I'll see. It will come to me in future. But anyway,your questions and points are right!
Any further experiences and notices i'll post here...

[Geo]

Well, what it made us :confused: and you spoiled it :mad: ??? I will show the photo to my children to eat all the food (he ..he)
My friend Regards

[Qiaozhi]

So,as planed,first step is finished. I just unsoldered all
components from pcb. To tell you the truth it was "labour".
But,have to say, White's used extra quality materials here.
Tribute to White's. The very best ever prepared pcb i saw
in my life. Holes are metalised,pads,vias superb!
I used my Salomon soldering iron,which is very good and
neither one damage occured! Pcb need some cleaning,so when
done, i intend to scan it on 600dpi.Later, using Corel Photo Paint
i intend to redraw all over photo,do some more cleaning,sharping
and finalizing to make file for offset printing.
I done reverse eng. same way,so many times on much originals
so far, but i have to repeat, this pcb is best quality i ever saw!
For now here is blured photos(my camera is modest).
I'll also post scans when done.
regards
P.S.
Esteban,although you explained pretty good, coils here,please can you
do some extra work. Can you use paint or simillar and draw more
preciselly inner composition of coils.. I didnt get quite clear
picture of those yet.Call me stupid,but i would like to be sure
what is all about.Dont want to make any mistake when making those.
Thanks in advance! Also everybody else, if somebody have pictures
draws&stuff about those coils,please come here and post.



Michael you made good points there! No, i didnt tested it detailed yet.
I intend too in future. But anyway i do have strong wish to make another...and maybe another...and another....ha,ha,ha! I'll see. It will come to me in future. But anyway,your questions and points are right!
Any further experiences and notices i'll post here...

Crikey!
The quality of construction may be good, but it looks like a mad man did the PCB tracking.

[Esteban]

Hi

Hope this can helps.

[ivconic]

scans


Regards to all!
Esteban you done great job now! Thank you!
Here is scans....Origin files are HUGE!!! 27Mb's, so it is quite impossible for me to upload those anywhere....I done some compression and here they are...I hope this degraded will done job anyway...I intend to post offset files when prepared, but it will take a week or two for me to done them...
Regards