Minipulse Plus Rev My time has come!

[green]

Inspired by your coils as a Sunday project i made this..All specs in desirable range but detection range little less than 3dss

[ATTACH]45987[/ATTACH]

How can i measure (or calculate) which coil is fast?

The way I do it. Been told there are better ways but it's the best way I have. Scope is looking at amplifier out of a operating PI. Set scope gain low maybe 100mv/div. Position test coil near operating PI coil for a reasonable signal on scope. Test coil is a different flat radial coil same as reply#58. 10nf cap is npo ceramic, 100nf cap is polypropolene. Measurements with my multimeter. Measure resonance and calculate either L or C with formula scope screen #2, frequency resonance=1/2pi/(LC)^.5.

[mushaba]

Flat spiral and flat basket I posted awhile back. Coil capacitance less than 1foot of lead wire. Don't seem to need spacing between wire wraps to reduce coil capacitance. Maybe another reason to space wraps?

Inspired by your coils as a Sunday project i made this..All specs in desirable range but detection range little less than 3dss



How can i measure (or calculate) which coil is fast?

[mushaba]

Hi guys,i dont know if i should be sad or happy..I still cant understand the hole dumping thing,please forgive me but my knowledge is incomplete in this area.

I've just connected the 3dss i made from 0.64mm ETFE cable.Here are the results:

Sad because i couldnt get the right size at outter diameter of 20cm.



Sad because i couldnt get the right inductance at 300-400 uH



Sad because i couldnt get the right resistance 3-4 Ohms



Happy because the coil works GREAT!!!! I detect and 1966 English gold coin at 25-30cm,i detect my chain with cross at 10cm and generally i detect gold!!!!!The can of soda starts at 65-70cm!!

Although i am happy i would like to learn,why all went wrong and the detection came out right?

Either coil worked fine for me. Fastest coils I've made. Haven't tried a 3DSS because baun7154 replied magnet wire didn't work good when he tried it. I had a large spool of magnet wire and wanted to use it. Guessing stranded would work fine.

Hi green,thanks for your reply...If you had more space between each wire in the spiral should it have less capacitance?How can i calculate the capacitance of my coil??

Hi Mushaba, I have no actual formula to point you to for line spacing. Looking at tesoro coils it looks like one to ne as far as i can see.
As far as a design I was wanting to try a flat DD . The one in figure 7 interests me .

https://patentimages.storage.googleapis.com/95/c1/54/17e56dd1fd86cc/WO2017015730A1.pdf

There were more stack example last I was looking but Im not finding them now Ill have to look around more.
Your shop sounds nice, your right i just have to buck up and do it ive been saving a couple older computers with windows 7 on them to dedicate to a mill Just too many projects and work right now.
As far as correct coil your 3d ss looks pretty good or are you looking for the ability to test below 6 us? Recent discussion is DD is the way to go as far as i can tell.
I have Itmd as well but have not been able to give it the lab time It deserves and right after i got it 2 came out so I still have to get it.
Your 3d ss coil should be pretty good for testing or are you looking for something super fast below like 6us?

Hi godigit1,thanks for your reply and the usefull intel..I would answer to your question (are you looking for the ability to test below 6 us) if i could but i dont,what do yoy mean by 6us?



How does this coil seems to you?

[godigit1]

Hi Mushaba, I have no actual formula to point you to for line spacing. Looking at tesoro coils it looks like one to ne as far as i can see.
As far as a design I was wanting to try a flat DD . The one in figure 7 interests me .

https://patentimages.storage.googleapis.com/95/c1/54/17e56dd1fd86cc/WO2017015730A1.pdf

There were more stack example last I was looking but Im not finding them now Ill have to look around more.
Your shop sounds nice, your right i just have to buck up and do it ive been saving a couple older computers with windows 7 on them to dedicate to a mill Just too many projects and work right now.
As far as correct coil your 3d ss looks pretty good or are you looking for the ability to test below 6 us? Recent discussion is DD is the way to go as far as i can tell.
I have Itmd as well but have not been able to give it the lab time It deserves and right after i got it 2 came out so I still have to get it.
Your 3d ss coil should be pretty good for testing or are you looking for something super fast below like 6us?

[green]

Thanks green for your reply!
So spacing between the wraps won't reduce capacitance?Did the coil you show work well?

Either coil worked fine for me. Fastest coils I've made. Haven't tried a 3DSS because baun7154 replied magnet wire didn't work good when he tried it. I had a large spool of magnet wire and wanted to use it. Guessing stranded would work fine.

[mushaba]

Flat spiral and flat basket I posted awhile back. Coil capacitance less than 1foot of lead wire. Don't seem to need spacing between wire wraps to reduce coil capacitance. Maybe another reason to space wraps?

Thanks green for your reply!
So spacing between the wraps won't reduce capacitance?Did the coil you show work well?

[mushaba]

Hi Mushaba,
Nice job on the coil and forms. Your Idea about the flat coil and using your mill to make a form is very interisting. I was wanting a desktop mill for some carbon fibre work but havent sprung for it yet.
I would think a wire width spacing would be good for your form and maybe two sided where the wire wraps around the inner or outer diameter and the wires line up in between the opposing wire layer.
Ive played with a few flat coils but they werent too good due to wire type next one will be DD. A form like your thinking would be perfect.

Hi godigit1,thanks for your reply!I was blessed in my life with lot of workspace,that gave me the comfort to collect tools year by year and make a workshop for my hobbies!Except the electronics which is my main job I'm a machinist wannabe,I have a lots of tools about turning paralleling drilling and welding..The cnc mill came due to electronics need for prototyping,it's a good way to assemble a pcb and if is all good you print it professionally,lots of pcb manufactures with great price.I would suggest if you are thinking about building a cnc Just do it as Michael Jordan said,it will give you a lot of "freedom" and flexibility..The mechanical and the electronic parts now days costs few hundrends,learn a cad program and you are ready to go!
Today a friend send me a copy of Inside The Metal Detector,man all the knowledge in there!!!I will try to read it before I decide about a spiral,it's good to experiment but is better to construct something with correct design if you know the physics behind that...As I understand the time that the coil "diggests" the spikes from the mosfets is how fast the coil is...The flat spiral should reduce capacitance due to wire spacing but what is the formula to decide what spacing should use?If you have anything I'm mind I will happily construct and test it.I am missing a good working coil to have as base to test my current MPP project and Mirage and Delta Pulse to come...But I must have a base and a correct coil is the thing I need right now.

[green]

Flat spiral and flat basket I posted awhile back. Coil capacitance less than 1foot of lead wire. Don't seem to need spacing between wire wraps to reduce coil capacitance. Maybe another reason to space wraps?

[godigit1]

Hi Mushaba,
Nice job on the coil and forms. Your Idea about the flat coil and using your mill to make a form is very interisting. I was wanting a desktop mill for some carbon fibre work but havent sprung for it yet.
I would think a wire width spacing would be good for your form and maybe two sided where the wire wraps around the inner or outer diameter and the wires line up in between the opposing wire layer.
Ive played with a few flat coils but they werent too good due to wire type next one will be DD. A form like your thinking would be perfect.

[mushaba]

That looks really good. Now you know why I stay away from such coils.

Yes, indeed dbanner!But desperate times requires desperate measures....Can you suggest me a good spec monocoil?

[dbanner]

That looks really good. Now you know why I stay away from such coils.

[mushaba]

It is my first time to such complex coil build,didn't notice little crucial detail such the one slot moving after 5 turns each time...At 25 turn I still moved one slot forward,instructions said front or back...ETFE cable 0.64mm I think.Im going to test it on Saturday,hope I nailed it!

[kt315]

Sorry,my bad,i did not transfer 1 slot every 5 turns...grrrrrrrrrrrrrrrrr...I hope it worth it

also, big mistake people are filling the coil by epoxy. DO NOT DO SAME -!
do a layer above by a rope diameter 3-5mm with a step 5-10mm . after that do 2-3 layers of skotch standart tape.
internal area with the winding has to be isolated (airy) and epoxy does not have to fill in it.
do shielding, graphite aerosole, layer inside your housing. melt a naked thin wire (i use silver covererd wire)
in surface of your graphite layer. you have to connect ground wire of the cable to it on end of job before finish epoxy filling.

[mushaba]

The "failed" one i can use it as AM radio antenna

[mushaba]

Brilliant work. The shield for these coils maybe better by painting the walls of the coil housing.

Brilliant was the guy who designed it originally,im just a "copier"...Turns out that design it to cad and make 3 of them was good because unwound the mistaken ones is hopeless....If my PTFE comes in time i will make a nice "vacum" formed housing,as for the shield as i said before i must be doing something wrong because everytime i try to shield i loose detection depth.