Fisher 1280 schematic + Stuart PCB´s

[Fred]

Hi all,
I have learnt so much from this outstanding forum, i had to participate.

I post here the schematic of the 1280x aquanaut detector, with parts list.
The "module" diagram is missing, but with the help of the part list , i found (on this forum)that it is almost the same of the 1266.
The schematic is very similar.Frequency is only slightly different (70 and 72.5 khz for the 1280)

Quality of the scan is bad,it comes from the original that was damaged by moisture.Definition could be better, but file would be too big.
My intention is to make a PCB for it someday.
I´ll also post 2 PCB´s i have done for the Stuart PI, the one using the 16F84 PIC.One with modifications,the other without.Parts placement is almost the same as the original.

Hope it will be useful.I i am loking for any (building) information about underwater detectors.
Fred.

[amtech2005]

Fisher 1280 schematic + Stuart PCb's

Thank-you for Posting !!!! Schematic needs some cleaning up , But will be a Great Project for Experimenting. Need Search coil parameters, but not necessary. PC Board Photo would be very Helpfull. I noticed the Big Jpeg "schematic" slows down the server on this Site, Ha-Ha. Excellent circuit and a lot of usefull information. Thanks Again , Eugene [email protected] or [email protected]

[Fred]

I should have resized the pictures,but i was afraid to loose even more in quality.
I can send the schematic splitted with better definition or a partial view, if needed.
I hope to hear from people who make progress on this schematic and with better knowledge than i have :maybe there is an equivalent diagram already known with similar capabilities.The 1266 is quite similar...
The crystal oscillator is interesting.This way we can be sure there is no VFO effect :-)

good luck.
Fred.

[amtech2005]

Fisher 1280 schematic + Stuart PCb's

Hello . The frequency to the coil is 2.4 khz. The missing module has a crystal frequency of somewhere around 70 khz ?? Correct me if im wrong. But anyway the schematic is 133 kbyte size jpeg , kind of big , maybe can be converted to another image format. The resistors are the hardest for me to see . As I have time I will pursue this further. It sure is a coincidence that other big detector manufacturers make 2.4 khz detectors with striking similarities . Thank-you for posting , that is why this forum is so Great . And Ive been on it for years now. Take care. Eugene [email protected] or [email protected]

[kt315]

similar to 1266. seems it is 1266, but underwater performance.

[Fred]

The 1266 have one more 4066 ic.The module is probably the same,except for the frequency.
Aparently the 76.8khz crystal oscillator is divided by the 4024 ic .
I will try to replace the schematic by a better one on Monday.
Working on the PCB .
Regards,
Fred.

[kt315]

where you propose to order/buy the crystal? I and others are in hard difficulty to find such low frequency one. are you in course that there is AVR and HEX file for it working at ANY frequencies? it is cool decision for anyone doing IB project similar to you did share. Ivan DID that

[Fred]

One strange thing is that Fishers says the frequency of the 1266 is 4.8 khz, but if we divide 70khz by 16 (this is how the 4024 is configured) it gives 4.375khz.

Anyway, the 1280 frequency is 2.4Khz and for a 76.8 crystal, we should use a divide-by-32 configuration).
BUT, could also keep the divide by 16 and use a clock 32khz crystal, that would give a frequency of 2khz.
I do have a couple of crystals somewhere (i think i was 100khz and one was lower in freq),but they are big.So i may try the 32khz idea.Anyway, i have almost finished the PCB, and when i get the parts i will make experiments.
Of course, the hex idea is good,but someone have to do it, :-)
I post here a better scan of the schematic, size is about the same, but quality is better. I tried to remove the other one, but i didnt figure out how.

Good luck ,
Fred.

[Fred]

Here is the PCB for the Fisher 1280.
Please note:
-I have not tested it,still waiting for parts.

-It may (and probably have ) errors,altrought i have checked it.

-The parts Nº refers to the schematic, for the "module"see the
schematic of the 1266.

-There is 6 jumpers, but they are all used also as test points.

-The TX and power supply circuits can be cut off and used separately from
the main board.

-On the schematic, Q404 is connected to +9V.There is no +9v on this
diagram,i suppose it means +12v (so it will not load the +6V supply).
Anyway, this transitor can be removed and jumpered between Collector and
emitter.It supplies power to the audio amp.If you choose to connect it to
+6V,as i planned at first, just solder a small wire between the pad
and the +6V jumper nearby.If not, connect it to the 12v after the power switch.

-I am not sure how the "battery test" works.Aparently it just open
both "audio ctrl voltage " and "discrimination circuits,so it makes
a loud tone.

-For the coils, i suppose any coil made for that working frequency (2.4khz
with the shown crystal) will work.comments?

-The 4024 ic is in a divide-by-16 configuration.(i made this for a 32khz clock crystal,as i plan to use 32,768:16=2048 khz).This configuration is also used in the 1266 detector with a 70khz(?)crystal,giving a frequency of 4.375 khz.(??)
if you want to use a 76.8khz crystal,(as in the original 1280 circuit),you should use divide-by-32,for this just connect pin 5 of the 4024 (instead of pin 6) to T1 transistor.

-I have choosen this PCB shape because for water proofing i will use a
thick wall pipe (aluminium or plastic), and "plexiglass" ends.

If you build this,i hope to hear from you....

Good luck,
Fred.

[tperez]

Fisher 1280X

Hi,
I have bought a water damaged 1280X.
All circuits seem to be in working order i.e. I get an audio, the sensitivity and disc. controls sound in good shape too and the battery check facility also produce a sound. The only thing that is not working is the coil. There is no detection when any metal object is passed over the head. I have checked the cold resistance of both the RX and TX coils and they read as 35 and 45 ohms. respec. Does anyone know if this is just about right?
Looking at the diagram supplied in this forum, there is no information on the crystal board where the coil leads connect to?
What should I be looking for when there is no detection as in this case?
I am sure this is easily repairable and would appreciate any info anone can pass.
Many thanks
Tony

[danl]

Hi,
I have bought a water damaged 1280X.
All circuits seem to be in working order i.e. I get an audio, the sensitivity and disc. controls sound in good shape too and the battery check facility also produce a sound. The only thing that is not working is the coil. There is no detection when any metal object is passed over the head. I have checked the cold resistance of both the RX and TX coils and they read as 35 and 45 ohms. respec. Does anyone know if this is just about right?
Looking at the diagram supplied in this forum, there is no information on the crystal board where the coil leads connect to?
What should I be looking for when there is no detection as in this case?
I am sure this is easily repairable and would appreciate any info anone can pass.
Many thanks
Tony

my 8" Spider Coil resistance, your's perhaps "cold" resistance...

1-3 : 40,96 Ohms
2-4 : 5,22 Ohms

Please send pictures of your 1280x pcb... thx

[nalag46]

Fisher 1280X

Hi,
Attached are pics. of my 1280X pcbs.
Can anyone pass any comment on my problem?
Thanks

[Unregistered]

hi nalag,

thank you for pics, il would like build this detector (1280x) from schematics of fred, would you send more some detailled pcb and components pictures. Thank you

[nalag46]

Fisher 1280X

my 8" Spider Coil resistance, your's perhaps "cold" resistance...

1-3 : 40,96 Ohms
2-4 : 5,22 Ohms

Please send pictures of your 1280x pcb... thx

Hi,
Can you let me know what voltage you read on both coils with the detector switched on (but coil not detecting).
My resistance on 2-4 is higher than your 5.22 ohms. It reads 19 ohms and the 1-3 or RX coil is 30 ohms. Mine is also an 8" spider coil

[Unregistered]

Hi,
Can you let me know what voltage you read on both coils with the detector switched on (but coil not detecting).
My resistance on 2-4 is higher than your 5.22 ohms. It reads 19 ohms and the 1-3 or RX coil is 30 ohms. Mine is also an 8" spider coil

hi, i have the same 8" spider coil than you but my MD is an 1235x. I will read voltages in about 3 days, i'am far from my home today, (500 km from Paris)