northwest My DIY metal detector project
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Some software and hardware updates now available for the QED.More  QED firmware updates (inc Auto GB  option) just announced here. New  QED hardware updates/options and pictures will be posted  first here  as they become available.

Another satisfied QED user! QED user report for 9 days detecting! User loves it, found it easy to use,found gold with it and he prefers it to his 5000! Also a report on a QED used at the beach for coin shooting.QED users reporting in with their multi ounce gold finds with the QED!
From  another QED user today:"Been out and about today testing and comparing against other machines etc in ground that has been horrible in the past.Bround balancing Ive found very simple and easy.'m using the Nokia booster but need a little more sound/threshold.Otherwise no complaints from me, very impressed."
and :"My QED with the 8” commander on it, out performed my SDC Got bits that don't register on my scales SDC has since been sold"
"My QED is terrific. Lightweight, very sensitive and screams at me when it hits any target. The Detect shaft and the 11" ultra sensing coil is a top quality fitout. I attached an external speaker which added under 200gms of weight in total and still remains very well balanced so i never feel fatigued after many hours of swinging."

Stinky  Pete :http://www.detech-metaldetectorsaustralia.com.au/ is the  Australian distributor for the QED.
This is the only forum where you can talk directly with the designer/ manufacturer of the QED and  also some very experienced QED users.
Jrbeatty and Reg Wilson  and  Yellowfin  (or Doug here for that matter!)have NO vested  or pecuniary interests(or secret deals or cash for comment or any other undisclosed benefits )in the QED other than using it to find gold which it is doing very successfully! The ONLY people deriving  an income from the QED(other than finding good gold) are the approved retailer and Bugwhiskers! The ONLY investor in the QED is Bugwhiskers!
I have never met Jrbeatty or Reg Wilson at Howards house or ANY other location!

australian electronic gold prospecting forum.com  |  DIY forum  |  DIY forum  |  Topic: My DIY metal detector project 0 Members and 1 Guest are viewing this topic. « previous next »
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Author Topic: My DIY metal detector project  (Read 5010 times)
mickstv
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« Reply #120 on: Friday January 10 2014 09:41:28 AEDT AM »

  
I am having problems with the simple floating ground works then doesn't i think i will just use 2 9 volt batteries this split rails driving me nuts .

I have the circuit going up to ic 6 pin 6 seeing the waveform and placing a metal object near the coil i can see a reaction on my little scope ,so this is a good thing ,i might as well hook the rest of it up see what happens .
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Well I tried to tell you the power supply setup wrong.

You will be better off either purchasing the ICL7660 (make sure its the 12volt input version) or a LT1054.  The other option is to use a 555 as a voltage doubler (Google it).

Also for this detector and any other PI,  9 volt batteries are a no no.  Go find a small 12v Gel Cell battery.
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harry dalek
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« Reply #121 on: Friday January 10 2014 19:29:32 AEDT PM »

Well I tried to tell you the power supply setup wrong.

You will be better off either purchasing the ICL7660 (make sure its the 12volt input version) or a LT1054.  The other option is to use a 555 as a voltage doubler (Google it).

Also for this detector and any other PI,  9 volt batteries are a no no.  Go find a small 12v Gel Cell battery.

Well 2 9 volt batteries seem to work now in driving the circuits , but your more than likely right on the type of batteries for use for a length of time ... my main problem was the dual supply hate dual power supplies at the best of times and this was hard one using 3 other power rails...

This is my first working one i am going to make others but i don't think i will make a hammer head again i have seen better PI designs less power hungry  less parts  .

I am finishing off this one now and see if i can get it cased up and work on getting it on the shaft .

Why do you need a voltage doubler ? the hammer head just uses it because thats all the chip does with a Ac out put so gives a way to get a common ground 5 volt positive with a regulator ...as far as needing voltage doubling part of it thats not needed at all ...the power supply part of the design is a bit messy ....if i knew what i do now i would just use 2 of my voltage converter ics it can do 4 times what the hammer head ic can do 
2 will give a positive or negative dual supply and i would also do away with the 2 7905 s  just wasting battery as heat ...

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mickstv
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« Reply #122 on: Friday January 10 2014 19:59:09 AEDT PM »

  
Well I tried to tell you the power supply setup wrong.

You will be better off either purchasing the ICL7660 (make sure its the 12volt input version) or a LT1054.  The other option is to use a 555 as a voltage doubler (Google it).

Also for this detector and any other PI,  9 volt batteries are a no no.  Go find a small 12v Gel Cell battery.

Well 2 9 volt batteries seem to work now in driving the circuits , but your more than likely right on the type of batteries for use for a length of time ... my main problem was the dual supply hate dual power supplies at the best of times and this was hard one using 3 other power rails...

This is my first working one i am going to make others but i don't think i will make a hammer head again i have seen better PI designs less power hungry  less parts  .

I am finishing off this one now and see if i can get it cased up and work on getting it on the shaft .

Why do you need a voltage doubler ? the hammer head just uses it because thats all the chip does with a Ac out put so gives a way to get a common ground 5 volt positive with a regulator ...as far as needing voltage doubling part of it thats not needed at all ...the power supply part of the design is a bit messy ....if i knew what i do now i would just use 2 of my voltage converter ics it can do 4 times what the hammer head ic can do 
2 will give a positive or negative dual supply and i would also do away with the 2 7905 s  just wasting battery as heat ...




The 7660 is also synchronized with the TX pulse,  this is done so as the 7660 is off during receive so you don't get 10khz osc noise being injected into the electronics.

I use two power supplies in my detector the first one is a LT1054 into a +5v reg it is used to supply the micro and audio output.  The second power supply uses one half of a mosfet driver IC TC4424,  this same IC supplies the TX pulse,  so all the op-amps get +5v that is synchronized with the TX.


P.S.  At the top of each users post you'll find an option to quote Reply with Quote,  if you wish to quote posts please use this option otherwise it makes your posts messy.
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moodz
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« Reply #123 on: Friday January 10 2014 22:10:48 AEDT PM »

Don't waste your money a couple of diodes and caps will voltage double using tx pulse.
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harry dalek
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« Reply #124 on: Friday January 10 2014 23:44:43 AEDT PM »



Oh sorry about that i can't see that Quote box , i use opera browser for some reason its just a little box no information ...pointing it out i know now . smile
My chips running at 100khz but i am still so so about the whole power supply and all the power rails i ran it by some Technician friends they were not impressed ,they also could not believe it used 555 and 5534 in a portable device as they eat the battery  power and they didn't like so many trimmers  .

Any case i am still happy the electronics works ...i can work on the rest of it now .
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harry dalek
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« Reply #125 on: Friday January 10 2014 23:59:23 AEDT PM »

Hi Moodz

Perhaps a voltage doubler would come in handy via a lm317 feeding the mosfet...wonder if just the transmitter transistor and coil had its own variable power supply you could adjust the transmit strength same as  if you were using a bigger coil with out having one .

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moodz
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« Reply #126 on: Sunday January 12 2014 09:44:09 AEDT AM »

...something for you ..a MOSFET driver cct has plenty of juice to drive a voltage dub. You only need to power the first amp.
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harry dalek
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« Reply #127 on: Sunday January 12 2014 18:34:40 AEDT PM »

  
...something for you ..a MOSFET driver cct has plenty of juice to drive a voltage dub. You only need to power the first amp.

I didn't think of that very true.

I am just casing up now and working out what panel controls i will use .

I only have had one problem i just fixed, i had to swap the VCO speaker circuit from negative battery to positive ground as i have a metal case ,the plugs common ground i would of been shorting  it out via the coils  ground plug on the case ....

I am just using one transistor Q7 after the vco 555 so that was easy to just swap the speaker circuit or head phone circuit around .

I also wound a new coil as my old one was for that VLF version ,..

I might do a video or so when the casing up is finished .



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harry dalek
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« Reply #128 on: Wednesday January 15 2014 20:19:53 AEDT PM »

I have been thinking about the coil housing for my Hammer head Pi and there are a lot of easy ways to do it and harder ways i suppose.

I have been looking at shapes people use and found this template ,after printing it out and seeing if i got the size right my coil fits with in it .

So i am going to cut this out and use it to cut out some plywood 2 copies and sandwich the coil between them, i will cut out the brackets for the slots as well then i will fiberglass around the thing .

I was thinking perhaps just cutting out the shape from a card board box with the fiberglass it might be strong enough as well ? perhaps i will try both to see .
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WM6
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« Reply #129 on: Wednesday January 15 2014 22:36:02 AEDT PM »

Plywood is hygroscopic, heavy and not dimensionally stable.

Try with extruded rigid polystyrene foam (XPS) plate for building thermal insulation.
XPS panels are available in different thickness can be easily processed, and then reinforced with synthetic fabric and an epoxy resin layer.

Like this:

  


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harry dalek
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« Reply #130 on: Thursday January 16 2014 14:34:58 AEDT PM »

Hi wm6

I am using very thin plywood i am going to layer it up for strength with fiber glass i agree there are better options !
They make surf boards out styrofoam sheets and fiber glass ,any thing that can hold its shape before you fiber glass it more than likely do .
The thicker boxes the card board could be another cheap option .
I think you are thinking i used a big lump of thick plywood no no ,i will take a few pictures as i go,i am going to buy the resin and fiberglass on the weekend .
The thin plywood will be incased in fiber glass water proof just like a surf board ...
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IBGold
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« Reply #131 on: Thursday January 16 2014 15:03:38 AEDT PM »

Hi Harry,

WM6's idea make a lot of sence and is what I use for my coil formers you can shape it route it out and wind the coil into it all sorts of things the stuff I use comes from Foamex and is blue the only thing is you can not fibreglass it as fibreglass disolves the Styrofoam you have to use Epoxy,  but for a one off the ply or cardboard will be ok as long as they are fully sealed but you will need to shield the coil for our conditions.

  There are other reasons for useing the Styrofoam that relate to dialectric constants I think you will understand.

Regards, Ian. happy face
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Regards, Ian.
turtleman
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« Reply #132 on: Thursday January 16 2014 17:04:29 AEDT PM »

Harry

Why not use two elliptical coil covers sandwiched together. You don't have to worry about making forms out of foam or fiberglass. On one half put your mounting ears, reinforced from the underside and then drill a hole for your coil leads.
Drop you windings in and fill with epoxy or 2 part poly foam. Once it's set up put the other coil cover on and epoxy together.
Done! Looks like a professional coil.

Tom
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harry dalek
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« Reply #133 on: Thursday January 16 2014 20:42:10 AEDT PM »

  
Hi Harry,

WM6's idea make a lot of sence and is what I use for my coil formers you can shape it route it out and wind the coil into it all sorts of things the stuff I use comes from Foamex and is blue the only thing is you can not fibreglass it as fibreglass disolves the Styrofoam you have to use Epoxy,  but for a one off the ply or cardboard will be ok as long as they are fully sealed but you will need to shield the coil for our conditions.

  There are other reasons for useing the Styrofoam that relate to dialectric constants I think you will understand.

Regards, Ian. happy face

Hi Ian
Thanks for the good advice i under stand that would be better to use only reason i am going this way is i have to make one and trying to do it on the cheap best i can ...easiest way i think i can do it with the tools i have and skills at the moment  .
I don't think this will be the only one i will ever make as i want to try and improve my results but i have to start some where and i am new to this but i don't want to use a frizbee or plastic plates ,least its a bit above that idea.
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harry dalek
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« Reply #134 on: Thursday January 16 2014 21:01:22 AEDT PM »

  
Harry

Why not use two elliptical coil covers sandwiched together. You don't have to worry about making forms out of foam or fiberglass. On one half put your mounting ears, reinforced from the underside and then drill a hole for your coil leads.
Drop you windings in and fill with epoxy or 2 part poly foam. Once it's set up put the other coil cover on and epoxy together.
Done! Looks like a professional coil.

Tom

I do like the idea of epoxy but i am not sure of the cost of filling some thing the size of a frizbee , i have seen they use wax to stop the stuff sticking and putting in shapes to use less of the stuff and drop the weight.
They only sell one type at bunnings and masters here in melbourne its clear and not really a big amount of it  ,i will look into it a bit more .
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harry dalek
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« Reply #135 on: Thursday January 16 2014 21:28:23 AEDT PM »

I do like the advice on the resin just cost and amount ,i have  to have a good look and see whats the cheaper way to go  .

I know with the fiberglass i will have enough for very little cost..little more messy  and more time.
As far as either way  what the end result looks like a pro coil casing i suppose it comes down to your skills it could go bad in the wrong hands . scared

Not so much sticking with my guns here but trying to see if it works for me ,i tried this today have not cut out the middle bits for weight loss or made the bottom but i sort of think it will end up lite .

I will work out some sort of spacer between the top and bottom forms for a thicker sandwich look.

Just see how it gos ...if it gos bad i will drop it gos good could not be worse looking than a plastic plate .



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harry dalek
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« Reply #136 on: Friday January 17 2014 12:32:54 AEDT PM »

To go any further with this idea i had to see if i could cut the harder bits out of the template,so gave that a go today and went ok .
Also worked out the brackets for the arm and slotted them in the holes, i will glue those in place and fiber glass the lot and make it all air tight .

I wanted to use a tiny coax plug to screw onto this coil case for my cable ,is it a better idea just to coax right to the coil
no metal plug at all ?
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authere
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« Reply #137 on: Friday January 17 2014 17:40:53 AEDT PM »

Hi Harry,

It's good to see you are seeing this project thru to the finish!!!!, as for using a coax plug and socket there would be two trains of thought with this, at the end of the coax we should have a connection to change coils so if you want to put it at the other end of the coax who cares!!!

If you put one at each end you will increase the o/a ohms of the coil and make it out of spec( M/L coils req. 0.5 ohms),but if you can allow for the extra ohms go ahead

With your coil, you could cut another piece (slightly smaller)to go in the middle to act as a former to wind your coil in and with the glassing you can get very thin fibreglass cloth used for model aeroplanes and use an epoxy two part resin to cover it, I would just use a resin to waterproof it all as it is only a one off, maybe just a gloss paint would do

My understanding of the HH2 is that it is a learning platform not a working detector, I would think there is way more to add to it to make a working detector, especially a PI. As for a beach detector I think we would be better using one of Bugsy's QED rehash for beachwork

Cheers Ron
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harry dalek
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« Reply #138 on: Friday January 17 2014 20:06:46 AEDT PM »

Hi Ron [/font]



Yes it depended on the circuit results ,looks like its workable,i just tested it with the new coil mounted on the bottom plywood template i cut out today.[/font]



Well at the moment i have them at both ends N connector at the top and a SHF version at the bottom ,i did notice today that the metal in the plug does get detected and you can sort of readjust things to get it to work with the plug close ,still thinking about it if i will use it.



Well ones all that needed really' i like the idea of using the coil to test on another detector i make ...any case i like being neat so it sort of like the neater way of doing it as above its a design problem.



Well i wound a coil already but your idea would work,and i would of done it but my coil fits it like a glove luck more than any thing !
I have to see what its like when i fiber glass it it really needs it the sides where the coil gos but i will test and see what would look best if the resin is see through the print out may show via the resin so no painting needed ,i will find out !





I think Carl on the geo forum would think its a working PI but i would not make this one again due to what i did learn .
My tec friends were not impressed they said a lot of the tranies and pots and wrong type of ics for a portable metal detector.
They are fussy i am just happy it works but the next one i make now knowing what to expect and how it works it can be done simpler i think .
I have not seen Bugsy's QED ? i will have to google that one .
I like this one and i saw on another forum some one redesigned it  with easier to get parts .

  

He was trying to simplify it the design looks good worth a try .
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mickstv
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« Reply #139 on: Friday January 17 2014 21:16:33 AEDT PM »

  

I think Carl on the geo forum would think its a working PI but i would not make this one again due to what i did learn .
My tec friends were not impressed they said a lot of the tranies and pots and wrong type of ics for a portable metal detector.
They are fussy i am just happy it works but the next one i make now knowing what to expect and how it works it can be done simpler i think .
I have not seen Bugsy's QED ? i will have to google that one .
I like this one and i saw on another forum some one redesigned it  with easier to get parts .[/font]


He was trying to simplify it the design looks good worth a try .


The HH is/was basically an experimenters platform with plenty of controls for experimenting with different timing.  Also the HH works well,  especially when you use all the correct components.

Why don't you get your tech friends to design a better detector,  seeing as they know so much  smile
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