Recent Discovery

[Mark-VA]

A guy found thisdetector in a wood pile at a local factory. Looked like it had been therefor years, weathered badly, shaft was broken and coil was busted. As achallenge they gave it to me. Two days later I installed batteries and lowand behold it came on. Couldn't find a manual so I went into experimentalmode and can say I was impressed with the air test (for a Chinaproduct).
To start with Ithought it was a single tone machine, dime and nickel gave a high tone, butadjusting the ground balance and the discrimination revealed attributes thatreminded me of the TDI. Now a nickelgives a low tone and a dime remained a high tone.
Next I took themachine to my test garden of over 10 years and was shocked to hear a repeatableresponse of my deepest targets.
Please note, I’mnot promoting Chinaproducts, only indicating what I found.

There is oneadjustment on the side that I’m wondering about not sure what it might be.
Would also likeinformation about this machine, the internet really doesn’t indicate when theywere manufactured or much detail.

[homefire]

Must be one of the Obscure ones for sure. Doing a gOOgle brings up little. Well Ya have one now, Eaa?

[dbanner]

Wow! Great find. Pictures of inside the unit would be nice.

[nickel_n]

the picture is not very clear.
what is the number after MD-xxxx Metal Detector?

[dbanner]

Could it be MD 318?

[Mark-VA]

Yes

[6666]

There is a bit about them on the net, there is a series of these machines,
here are some instructions
https://www.instructables.com/answer...-work-its-got/

[steaua581]

A guy found thisdetector in a wood pile at a local factory. Looked like it had been therefor years, weathered badly, shaft was broken and coil was busted. As achallenge they gave it to me. Two days later I installed batteries and lowand behold it came on. Couldn't find a manual so I went into experimentalmode and can say I was impressed with the air test (for a Chinaproduct).
To start with Ithought it was a single tone machine, dime and nickel gave a high tone, butadjusting the ground balance and the discrimination revealed attributes thatreminded me of the TDI. Now a nickelgives a low tone and a dime remained a high tone.
Next I took themachine to my test garden of over 10 years and was shocked to hear a repeatableresponse of my deepest targets.
Please note, I’mnot promoting Chinaproducts, only indicating what I found.

There is oneadjustment on the side that I’m wondering about not sure what it might be.
Would also likeinformation about this machine, the internet really doesn’t indicate when theywere manufactured or much detail.

Can you post a video with an air test on a coin? just out of curiosity....

[homefire]

A little info : http://enshop.ebdoor.com/Shops/70556...cts/17534.aspx

[dbanner]

Any idea on the price? From pic of PCB, looks like a pretty decent and well made unit. By the way, what's a 4093 chip doing on a circuit like this? I see a quad comparator, 3 quad opamps and one of 4016, but 4093? I wonder its purpose.

[Skippy]

The 4093 may be part of the 'low voltage alarm' circuit.

I wonder what the function of all the missing components is? Maybe the next model in the range has these features extra?

[Skippy]

"the internet really doesn’t indicate when they were manufactured"

Your one appears to have chips dated 1995, though the PCB shows a date of: week 10, 1999.

[sinclairuser]

i have come across these before they are well made and work well, they are chinese but they are made and built by one of the proper manufacturers.
by that i mean they design and build their own machines, they dont copy other designs or try to pass them off as something they are not.
simple stuff well done, exactly what china should be making, believe it or not they have even been copied by the shenzen **** show, those are easy to spot as they have rubbishy black cases and the usual flimsy china stem and 5""omega coil, the board inside those are half the size of yours and look like a chimpanzee soldered it up.
as you can see from your photo the board is not bad, with proper components this could be a worthwhile build.
i would never bother re_engineering chinese stuff normally but this is different, the way it works could be enhanced and improved, a nice detector could be built out of this design.

[Mark-VA]

I was thinking the same thing sinclairuser.
Several attributes caught my interest right from the gate.
Very good discriminator.
Discriminator combined with ground balance changes tone of some targets, reminded my of the TDI.
Depth will match some high dollar machines.
I would like to know more about the machine, frequency etc.
Amazing for a China produced machine.
I think it would be worth investigating how they accomplished some of these performance improvements.
But I hate the handle and the balance is terrible to say the least.
The audio is mono so you only hear a response from one ear phone side.
I'm beginning to believe it beats the White's V3i and the F75 on my deepest test garden targets.
But the TDI is still the winner in my bad ground.

i have come across these before they are well made and work well, they are chinese but they are made and built by one of the proper manufacturers.
by that i mean they design and build their own machines, they dont copy other designs or try to pass them off as something they are not.
simple stuff well done, exactly what china should be making, believe it or not they have even been copied by the shenzen **** show, those are easy to spot as they have rubbishy black cases and the usual flimsy china stem and 5""omega coil, the board inside those are half the size of yours and look like a chimpanzee soldered it up.
as you can see from your photo the board is not bad, with proper components this could be a worthwhile build.
i would never bother re_engineering chinese stuff normally but this is different, the way it works could be enhanced and improved, a nice detector could be built out of this design.

[dbanner]

"Looks like a chimpanzee soldered it" ha ha! Pictures of top and bottom please, I will reverse engineer and draw schematic.