IB Rx coil at Tx off

[ZED]

Gold nuggets vary wildly. I have a 2-grain that's more difficult than my 1-grain. Lead shot is far more uniform. If you can detect a #9 pellet then you can detect most 1/2 grain nuggets.

Indeed ! I met a colleague up bush and he showed me a thumb nail sized nugget that he wanted to show off,he was particularly interested in waving it over my project detector,i asked him why and he said its almost impossible to detect,i looked at it and said "mate its the size of your thumb what are you on about",and then he proceeded to wave it over his coil and i was dumb struck by what i saw,he literally had to rub it on his coil just to get a faint signal from it,i thought that cant be right so i switched my machine on and waved the nugget over my coil and it came through loud and clear,upon inspecting the nugget it was heavily layered like sheets of paper,anyway to finish off ....the way the coefficients of the sampling and sample delay are on my detector it allowed me to hear the nugget loud and clear,it was a real eye opener about what nuggets still lay buried in the ground.

[Qiaozhi]

Indeed ! I met a colleague up bush and he showed me a thumb nail sized nugget that he wanted to show off,he was particularly interested in waving it over my project detector,i asked him why and he said its almost impossible to detect,i looked at it and said "mate its the size of your thumb what are you on about",and then he proceeded to wave it over his coil and i was dumb struck by what i saw,he literally had to rub it on his coil just to get a faint signal from it,i thought that cant be right so i switched my machine on and waved the nugget over my coil and it came through loud and clear,upon inspecting the nugget it was heavily layered like sheets of paper,anyway to finish off ....the way the coefficients of the sampling and sample delay are on my detector it allowed me to hear the nugget loud and clear,it was a real eye opener about what nuggets still lay buried in the ground.

You missed out some important information ... what detector was he using?

[Altra]

Ok i tried tinning some MLCC 1206 COG caps,4x33nf and 2 100nf,each 100nf cap was from a different batch.With the 33nf caps there was no change in capacitance after tinning,with the 100nf caps they changed there value after tinning by about 10 to 20pf.
I use the 33nf MLCC caps in a differential integrator cct and so i need to match them,but im still on the fence as to whether MLCC caps are better or PP thru hole caps are the way to go.

I have been using Panasonic ECHU pps caps for critical applications. Not cheap but you can find them on Ebay. Most of the footprints are 1206 or larger

https://industrial.panasonic.com/ww/...tor/echu/index

[waltr]

I have been using Panasonic ECHU pps caps for critical applications. Not cheap but you can find them on Ebay. Most of the footprints are 1206 or larger

https://industrial.panasonic.com/ww/...tor/echu/index

Those are great in the critical circuits.
At work we use them for filters.

[ZED]

I have been using Panasonic ECHU pps caps for critical applications. Not cheap but you can find them on Ebay. Most of the footprints are 1206 or larger

https://industrial.panasonic.com/ww/...tor/echu/index

Thanks dude, there worth a look,i will try some and see how they measure up.

[ZED]

You missed out some important information ... what detector was he using?

Qiaozhi you are right,the detector was either a 4500 or 5000 GPX series,i put the poor signal response down to the nugget having a very short time constant,the sample delay on my detector can be as low as 7.5 u/s,so its for this reason that my detector responded as well as it did.

[6666]

Qiaozhi you are right,the detector was either a 4500 or 5000 GPX series,i put the poor signal response down to the nugget having a very short time constant,the sample delay on my detector can be as low as 7.5 u/s,so its for this reason that my detector responded as well as it did.

Hi Zed, are you useing your own design or a modified / enhanced version of something thats been on Geotech for our hot ground ?

[ZED]

Hello 6666

My own design,i used to tinker alot with M/lab machines and then went on to designing and building my own detectors,playing with M/lab detectors taught me alot,it also helped me to steer around there I.P. and come up with my own ideas.

[6666]

Hello 6666

My own design,i used to tinker alot with M/lab machines and then went on to designing and building my own detectors,playing with M/lab detectors taught me alot,it also helped me to steer around there I.P. and come up with my own ideas.

Good work, sounds like you are on a winner, cannot wait for this stage 4 lock down to finish.

[ZED]

Yeah you and me both ! This curfew which they will probably extend will end badly for the state and Australia as a whole,i dont have any income at the moment and extending the curfew means i need to borrow more money again....credit doesn't last forever,something is going to break.

[green]

Well i have a quarter and a GPX4500 and an 18" mono but i need to go bush to see if i can get the same result,testing in suburbia gives me poor results but its winter here so its going to be a while before i get to the bush,once done
i will give you the results.

Hi ZED, have you had a chance to test a quarter in the bush? Wanting to test detection distance with 1A peak current control disabled. Looks like I get about 3A peak when disabled(324us on time). Have to go outside to test, less noise. Want to test detection distance for a coke can also. Added a 500V snubber(five 1N5378B's, 100n cap and MUR460 to coil hot)looks good. Might have to increase delay time with the higher Tx current.

[ZED]

G'day green........Mate im stuck with a lock down curfew,that means the Emperor who runs this state of Victoria says no one is allowed to travel more than 5 kilometers from there home and travel is only for very important reasons,and no citizen of this state is allowed out doors between 8pm and 5am,theres also talk of extending this curfew another 6 months.
On a brighter note i did do a test with a quarter using an 8" mono coil in the wee hours of the morning at home,the result was a steady but faint signal at 14",at 15" it was mixed,also with a coke can i get between 4'2" and 4'5" ,that's with an 18" mono coil using various m/lab machines as well as my own project detector,my own detector generally finishes a large TX period with 4 amps at switch off.

I think it may be a while before i get to the bush so yer gonna have to be patient but its definitely on my to do list.

[ZED]

Also an SD2000 sees a coke can at 3'4" with an 18" mono.

[Ferric Toes]

Also an SD2000 sees a coke can at 3'4" with an 18" mono.

I will fire up my Goldscan 6 and see how that does on quarters and coke cans. I only have 14in and 24in coils though. I also have an SD2100 for comparison but it is missing its 4 pin power plug on the control box. Do you know the pin connections for phones and power? I have a compatible plug.

The capacitor posts are interesting. The MMK5 through-hole ones I use change value when held with finger tip heat on the case. The radiated heat from a soldering iron held close, raised the value on one test from 96nF to 101nF.

Eric.

[ZED]

G'day Eric

To be honest the temp coefficient of the caps in the signal chain didn't have my attention till the subject was raised,i generally focus on the dissipation characteristic of the capacitor,i like to use caps with a dissipation below 0.009,generally
polypropylene caps (thru hole) are ideal as are MLCC in the COG spec,Polyphenylene sulphide (PPS) caps are my next choice if PP caps are not available,i generally steer away from polyester caps in the signal chain because of there higher dissipation.Again to be honest i make these choices based on what i have observed detector manufactures use,if im not sure of the direction im going then i will follow by example.

I will get back to you with the power plug pin out.
Are the 2100 timings of interest to you ?