control for multi field pi coils

[bernte_one]

hello

i got an used schiebel AN 19/2 mine detector coil.
while cutting the plug off i got an idea for a control switch for "multi field pi coils".

for example:

first positon- only inner coil is conected
second - only outer coil
third - both together in serie

its clear that in every case for each position another damping resistor has to added and also that the control trimmers have to be adjusted new

but the advantage ist that you have three coils in one

there are some more details in my plan but thats the main thought.

im not sure how to realize in practice if with mechanical multi switch or push button switch.


please let us discuss about it - i think of use this for one of my next detectors (surfpi pro or baracuda)

regards

[Rumcajs]

[QUOTE=bernte_one;148264]hello

i got an used schiebel AN 19/2 mine detector coil.
while cutting the plug off i got an idea for a control switch for "multi field pi coils".

Hi,

the Schiebel AN 19/2 is an military PI-detector with the separate transmitter and standalone receiver coils.

From head: the transmitter coil is 22 or 24 turn from 18x0,2 litze -- transmitter coil dia approx 19cm, while the receiver coil is 16x0,1mm litze 33turn and the dia is cca. 13cm.
That is relative small coils to deeper relic (treasure) hunting.

2nd, what do you think from this: the reciver coil is good for transmitting?
Im dont known...

The third problem is the pulse width: the pulse width in this detector specially setting is the hardly detected small parts only.
-- one known landmine include only 1,5 gramm(!) hardly detected antikor metallic material. This metal part dimension is very similar then average 3,5mm headphone connector (approx 3x12mm only visible!). It is all metal part of the full landmine!

According with the Mr. Rogowsky (bbsailor) comment (sorry I'm dont remember, anywhere in the Geotech-forum)
-- the best detecting one material type is must be the Tx pulse width, and
-- the second material type must be setting is Ty pulse widht for best detecting.

However, in this case must be changed the head, and minimum the timer parts of the electronic.

The one possible theoretic implementation is for your idea:

1.) one NE555 with an counter circuit. The counter enables 3 output:
step1 to one, step2 to two, and step3 to three, and repeating.
2.) 1st and 2nd otput form 1) is driven an 556 pulse generator (pps ad pwidth are separated)
3.) both pulse generator is driving the one independent power FET (ie. IRF 740 or IRF 9640) via opto-coupler
4.) the logical circuit (maybe diodes only?) if counter is steppping to 3. pos
it is enabling both transmitter.
5.) if FET-s is driving it coils (one to smaller, and 2nd to bigger): no damping res problem only once.


good hunting

rumcajs