Professional Systems Treasurehunt-Device

[Funfinder]

Yes! Meanwhile I could find and recover my very first MD-schematic from many years ago!

It was offered in some no longer existing selfbuiltable-electronic-devices-catalogue.


The describtion claims that the maximum detection distance is 1,5 meters (with a 25cm coil) !!!
If this would be true of course it would be fantastic!

Could somebody please check out what kind of circuit it is (probable P.I.) and
if the schematic already is correct or instead one of the described connection variations?
The paper with the drawing on it was in pretty bad condition but I really did my
best to recover the schematic!

Enjoy!

[bernte_one]

i think it is not a pi the way to tune frequency speaks for some kind of bfo it is a single coil and some windings to much for pi

[Funfinder]

Thx for the info, and perhaps the quartz also speaks for BFO.

I have now translated the parts-list into english and below also is attached the
complete how to built this device manual (still german but should be no problem).
The formerly price of the kit was 45 deutsch-marks which meanwhile are worth
around 50 Euro (inflation etc.).


Useful technical details:

There is some coil-shielding with the silverplated-copper-wire and stripes of alufoil.

The both coilcable-wires have to be shielded, with those both shielded cables inside
another shielding. The shielding is connected with the coils-shielding and with
soldering spot "J5".

Adjusting the sensitivity is done by the potis.

The speaker may have ca. 4-8 Ohm impedance.

Voltage: 16-24v DC (two 9v block-batteries work)
power consumption: 10-40 mA
depth with 25cm coil: up to 1,5m (for very large objects)
(larger coils should be even deeper)

[bernte_one]

ok thanks
16-24v can be delivered from a 4*18650 holder (cheaper than 9v)
the documents seem also from some other Version (if you lokk the pcb Pictures) also the entry article in the product order info says it can be powered from single 9V

if you make also a Little pcb layout i would build it too
but take care of the trimming capacitors, this should be a modern common type the parts from building document seems like old Radio parts ;-)

[Funfinder]

Drawing a pcb layout should be no problem by using the sketch from the #1 page
but first it would be good to be shure what are the correct connections of IC3.


This is some Dual D Flip-Flop chip for simple digital operations (CD4013).
Also the IC1 (CD4093), this is a schmitt trigger for digital NAND calculations.


I guess I can find out the real working chip-connection just by looking at the interal
chip pinout and design.


What's really helpful in this case would be some circuit-simulation software!
It should have no problem to emulate the used ICs.

Do you know any or is someone else here who is experienced with such programs?
Because I am not.


The PCB shown in the catalogue seems to be just an older model.
It looks that both have pretty the same parts in use and also the Number 16444 is identical.
In the catalogue they write 9v and on page 1: 16-24v so I guess the circuit we have
is the updated or improved version.

btw. when I built it for the first time I couldn't get it to work.
Too few experience, perhaps too much coil-shielding or something overheated -
hard to tell meanwhile what went wrong.

So of course I have a "good" amount of "unfinished business"-motivation!

btw. This is called the Zeigarnik-Effect.

The Zeigarnik Effect is the tendency to experience intrusive thoughts about an objective that was once pursued and left incomplete (Baumeister & Bushman, 2008, pg. 122).

http://www.psychwiki.com/wiki/Zeigarnik_Effect

Also responsable to try again and again to beat the end-bosses in video-games
and to solve the complete game to get satisfaction and the feeling to be a winner.

Meanwhile with the help of the very experienced forum members here and
perhaps also with the help of electronic-circuits simulation software it should
be possible to get it to work and perhaps even to improve it.

So bernte many thanx for your interest.
And perhaps we even can still find some of the original PCB anywhere.
I think that I still have stored the old catalogue with the contact-data.
Such special stuff usually goes special ways and is not lost that easily.

[bernte_one]

some people here are experienced with ltspice
i often thought about to try it by myself seems not too complicated

i know the seigarnik effect since my days if played ninja turtles or double Dragon in my childhood
and now it´s the same in electronic Projects ;-)

[Qiaozhi]

some people here are experienced with ltspice
i often thought about to try it by myself seems not too complicated

i know the seigarnik effect since my days if played ninja turtles or double Dragon in my childhood
and now it´s the same in electronic Projects ;-)

I highly recommend this [classic] book by Paul Tuinenga -> http://www.amazon.co.uk/SPICE-Circui...+paul+tuinenga
Although it's targeted at PSpice, the information is very relevant to LTSpice.

Or you could spend a bit more money and get one specifically for LTSpice -> http://www.amazon.co.uk/The-LTSpice-...0_SR112%2C160_

[Gwil]

The connections to IC3 shown in the main schematic are definitely wrong. Suggest checking against the 4013 data sheet.

[Gwil]

Also, the connections around IC1 don't make sense. For example, pin 11 (an output) is linked to the positive supply, and the crystal is connected across two inputs so there is nothing driving it. There would be no point in building this until the schematic is OK. Sorry.

[Funfinder]

thx for the input and interest.
Meanwhile I have found the address but I guess the company no longer exists - no personal website etc.
http://www.elektroatlas.de/elektro-s...kulmbach-17700
edit: in January 2013 the Salhöfer shop still existed:
http://www.pointoo.de/Frage/Kulmbach...ik-noch-56596/

Perhaps I have some luck when I contact Mr. Salhoefer personally.

But they had so many different electronic-stuff in the catalogue (our MD was at page 190)
that I guess the chances meanwhile so many years later are pretty low.