DIY coil for Fisher Gold Bug DP

[pnp007]

Noisy when touching grass usually means it's not shielded...

I have a cheapo that I'm trying to open the coil. For the last month
I've been running an Xacto around it to separate the half's. Maybe
I'll be in by New Years!

I'd love to see the schematic to that Goldbug above. It looks like
and updated one using a PIC. I've just started experimenting with
those, it's a blast writing code to make it do what you want!

my coil same as bernte_one. already shielded. but still noisy.

[bernte_one]

hello
oval clone coil runs at 3mV null volltage
all shield from goes to cable which is connected to pin1 from plug
i can find no point where shield from tx (pin 5) goes to coil its only shield from cable
pin1 and pin5 from connecting socket are linked so shield ist completed

extra nulling coil is not for set right null voltage like i supposed before
i think it is use to set right inductivity to achive the best relation of tx/rx frequency

i made a simpel dd coil without this mini tuning coil and my coil semms to be disharmonic
can detect at good distance and i get also a vdi number but it makes also some constant beeps (like false signals)
i hope a little tuning coil parallel to tx can solve this problem

also i wonder whats sens makes the resistor R2 from coil coonecting pcb?

mabe i can make a short video that you receive an impression of the work

regards

[bernte_one]

got the diy coil perfect nulled 0,00mV ac
but the display show overload warning
all clear now problem was my concrete floor
after lifting the coil up and pushing ground grab in all metal mode the light tickling sound disappears
now i am able to detect with the diy coil without any noise indoor
have to fill the coil with epoxy and will test it outdoor

resulst and pictures asap

kind regards

[pnp007]

very good job my friend. i hope you can share detail with me. what about coil 11" provided with detector?. can you make it function correctly?

[pnp007]

Why black 11 inch coil cannot ground balance?. not proper nulling the coil?

[bernte_one]

oval standard coil from clone has bad shield and coil is only fitted with hotglue so a knock with the finger can make a signal
senseless to repair this
you have to open whole coil

another think ist wrong wire size for rx (i think original has something under 0,2mm)
so resistance is maybe too low

[pnp007]

thanks for the explanation. i also have oval t2 coil clone. same as fisher oval coil clone. all of coils are bad. but white coil 5 inch and t2 white 15 inch is ok.

[Germanicus]

...now i am able to detect with the diy coil without any noise indoor
have to fill the coil with epoxy and will test it outdoor

resulst and pictures asap

kind regards

Can you tell us any update? already testet on Field?

[bernte_one]

hello

had some spare time to make a video

[pnp007]

hi, what about auto ground balance?.

[bernte_one]

auto gb works, no problem
problem indoor is more that i have danger to activate the overload warning
because there is all metal around coil

so best seems to make the hole setup procedure outdoor in the garden

[Germanicus]

Hi Bernte_One,

could you check, if my sketch is so o.K.? I am not shure how to connect the shields of the coils, connectorcase and the cable. What about Pin 5?
(Schirm=shield, Kabel = cable, Stecker = connector, Gehäuse = shell or case, Spule = coil)

[bernte_one]

hello

the whole shield from coil
coil shell
tx part
rx part
goes over the cable to pin 1 (should be rx gnd)

pin 5 is only shield from electronic box which goes over the coil cable shield down to coil
but it seems at my clone coil not connected on shielding coil shell (but makes sense for me)
so you get a full shield

i suppose at one point the pcb board is connected to shield from e box too

[Germanicus]

What surprises me is that the shield of the coil goes to the receiver coil, would rather expect to pass the interference to the transmitter coil to keep the receiver coil trouble-free.
According to your description this plan should fit:

[bernte_one]

plan2 looks good