C-SCOPE PULSE INDUCTION CS6PI

[DIRCEU]

Hi! EUGENE

What about the performance of CS6PI?
Is possible to make it?
Could you post the photos here?
Huff! I did a lot of questions today

Thanks in advance

DIRCEU

[Eugene52]

C-SCOPE PULSE INDUCTION CS6PI

Hello DIRCEU , I am working on the photos , and I am reading the field tests of CS6PI before I post them here . I am not sure if I have a schematic on this particular model . Normally the C-Scope schematics and alignment procedures are 1 to 2 megabytes in size . I am looking for that now and will post what I can later today . Is the CS6PI Discontinued ??? ...Take Care......Regards...........Eugene52/stalni-clan

[Eugene52]

C-SCOPE PULSE INDUCTION CS6PI

Here are clear photos in separate zip-files . And the fuzzy schematic is almost clear , but I do not know its accuracy , or if it is complete !!!!....Only the "CS4PI" model has very good field test results , maybe because it has a powerfull pic-chip . The "CS6PI" shown here today , does not have a pic-chip and the field test results were not as impressive , but it can be a great experimental-project !!!!..................Regards...........Eugene

[aft_72005]

Hi Eugene52
Thanking you, Circuit diagram didn’t has perfect resolution.
The nice circuit schematic now . by veltex
Best regards.

[DIRCEU]

Hi! EUGENE

Many thanks for all.
WOW!! Very nice photos.
I want start this project because I Think its easy and the components are found easily too ...but before that I shall conclude WHITES PI 1000 and TGSL which are almost ready.

Best regards
DIRCEU

[simonbaker]

Here are clear photos in separate zip-files . And the fuzzy schematic is almost clear , but I do not know its accuracy , or if it is complete !!!!....Only the "CS4PI" model has very good field test results , maybe because it has a powerfull pic-chip . The "CS6PI" shown here today , does not have a pic-chip and the field test results were not as impressive , but it can be a great experimental-project !!!!..................Regards...........Eugene

When building project, don't forget to make small dimple in capacitor C19 with soldering iron, it will not work without it.

-SB













couldn't resist...

[Eugene52]

C-SCOPE PULSE INDUCTION CS6PI

SimonBaker , it is now a special value capacitor . Speaking of modifications , If I remember correctly a forum member who has been here on Geotech "since its beginning" made a modification to this CS6PI machine . And it improoved depth by 30% , I am searching for his modifications he posted . I wish my memory was better sometimes !!!.................... Anyway SimonBaker , Have you noticed , since you joined the Geotech forum how many Metal Detector circuits have been modified and work much better than when they were new ??? I think the Metal Detector manufacturer tell's it's engineers , ok the entry level model must be designed with a maximum depth of 6 inches , and our mid-range priced detectors must not exceed 9 inches and the top of line must hit maximum of a 12 inch depth . And if they accidently release a top of the line "performer" at a mid-range price , within a year or less , it mysteriously gets discontinued !!! A good engineer makes great design's , but it is up to management to approve or reject it !!!......................So , A great opportunity and "electronic challenge" is always here , on the "Geotech Forum" to upgrade and improove Low to mid range priced metal Detectors . In the next 6 months "through the winter" on this forum , I predict we will see some successfull completion of projects like the Relic Hawk , Golden Sabre Light , and a possibility of seeing the "USB programmable Hammerhead" . I hope everyone is here throughout the long winter........Thanks all.......Regards..........Eugene

[headshed22]

New to forum

Hi all.
I have just bought one of these detectors for the purpose of experimenting with it, unfortunately the previous owner had opened the unit up and messed up the wiring in the battery box to the speaker/ headphone socket/ charger etc. also the two trimmer pots on the pcb have been tampered with. Resulting in a very low audio level and eratic threshold. I have been searching to no avail for any setup details regarding the unit and a diagram or clear photo of the wiring to the audio/ charging jacks.

It will be nice to do some mods later on such as in an old post on this forum by bbsailor, and then on to some of my own experiments and play with some diy coils but first I need to get the unit working properly as the factory intended to provide a reference point.

If anyone requires any photos or component values or any other information I can give then just ask.

Also if any members has any of the above info I require, it would be a great help to me.
Thanks all, great forum.
Russ.

[simonbaker]

SimonBaker , it is now a special value capacitor . Speaking of modifications , If I remember correctly a forum member who has been here on Geotech "since its beginning" made a modification to this CS6PI machine . And it improoved depth by 30% , I am searching for his modifications he posted . I wish my memory was better sometimes !!!.................... Anyway SimonBaker , Have you noticed , since you joined the Geotech forum how many Metal Detector circuits have been modified and work much better than when they were new ??? I think the Metal Detector manufacturer tell's it's engineers , ok the entry level model must be designed with a maximum depth of 6 inches , and our mid-range priced detectors must not exceed 9 inches and the top of line must hit maximum of a 12 inch depth . And if they accidently release a top of the line "performer" at a mid-range price , within a year or less , it mysteriously gets discontinued !!! A good engineer makes great design's , but it is up to management to approve or reject it !!!......................So , A great opportunity and "electronic challenge" is always here , on the "Geotech Forum" to upgrade and improove Low to mid range priced metal Detectors . In the next 6 months "through the winter" on this forum , I predict we will see some successfull completion of projects like the Relic Hawk , Golden Sabre Light , and a possibility of seeing the "USB programmable Hammerhead" . I hope everyone is here throughout the long winter........Thanks all.......Regards..........Eugene

I would not be surprised if your conspiracy suspicions are right!

I do think we tinkerers have an advantage over mass production because we do not have to design conservatively for stability. We can measure parts, replace if a little out of spec, trim pots, push the limits and not worry about complaining customers.

I suspect a major amount of engineering nowadays goes into fancier and fancier discrimination and target id, and that you can get very good depth with a cheap detector if they wanted to make one, as you suggest. The holy grail is to find that cheap detector which a small mod makes a nice deep machine with no frills.

Molzar's tests with TGS he bought make me eager to try a homemade double-D with my Tesoro Compadre to see what happens.

I hope to get a TGSL working this winter. I'm just very slow with PCB, picking one where my parts fit, only the mods I want, etc. Of course making coil and mounting in case and rod is always difficult for me with no workshop. I'll keep trying.

Regards,

-SB

[headshed22]

beginner starting work

Hi all
Having thought about reworking this detector a little starting from the PCB up, one of the first improvements that struck me would be to change the audio amplifier to an IC instead of transistors cutting down on external discreet components at the same time, something along the lines of an LM386N chip.

Having noticed from posts on the forum that the design of the audio stages in metal detectors seems to be somewhat neglected and whilst I can understand the principle of “if it makes a beep then it works” strategy wouldn’t a higher quality amplifier give better, more sensitive results? After all it is this tone and/or amplitude that we ‘read’ as a signal.
While not referring to hi-fi levels of audio, I just mean some improvement.

As an almost complete beginner at this, with limited equipment & experience, although a little common sense I thought it would be a good place to start before moving on to modifying other parameters such as altering the pulse frequency and sampling, and making a faster coil etc.

Do any members have any thoughts on this as a starting point to modifying the 6PI? It would be good to get some feedback and maybe some moral support that I am heading in at least the right direction.

Best Regards to all,

Russ.

[simonbaker]

Hi all
Having thought about reworking this detector a little starting from the PCB up, one of the first improvements that struck me would be to change the audio amplifier to an IC instead of transistors cutting down on external discreet components at the same time, something along the lines of an LM386N chip.

Having noticed from posts on the forum that the design of the audio stages in metal detectors seems to be somewhat neglected and whilst I can understand the principle of “if it makes a beep then it works” strategy wouldn’t a higher quality amplifier give better, more sensitive results? After all it is this tone and/or amplitude that we ‘read’ as a signal.
While not referring to hi-fi levels of audio, I just mean some improvement.

As an almost complete beginner at this, with limited equipment & experience, although a little common sense I thought it would be a good place to start before moving on to modifying other parameters such as altering the pulse frequency and sampling, and making a faster coil etc.

Do any members have any thoughts on this as a starting point to modifying the 6PI? It would be good to get some feedback and maybe some moral support that I am heading in at least the right direction.

Best Regards to all,

Russ.

Anything you try is a good way to "get your hands dirty". I don't know much of this circuit at this time so can't advise whether audio improvement will yield much, but it gets you thinking. I personally think the fastest way to learn is to breadboard the circuit (or parts of it), even though breadboard will be very noisy and not as good as finished PCB. Also use simulator such as LTSpice to analyze small sections of circuit where you have questions or want to try ideas.

If you have an oscilloscope (dual trace usually needed) you can learn a lot. Without an oscilloscope, you are stuck I think.

Cheers!

-SB

[bbsailor]

"Do any members have any thoughts on this as a starting point to modifying the 6PI? It would be good to get some feedback and maybe some moral support that I am heading in at least the right direction."

Russ,

The CS6Pi is a low power pulse detector. Do not try to make a high power unit out of it as you will fry the small 4-pin MOSFET IRFD113. Note there is a 39 ohms resistor in series with a 10 ohm CS6PI coil made with 30 turns of AWG 30 wire. This coil is designed to work at about 15 to 17uS delay only. If you want any faster delay you will need to remake a new coil with about 19 turns like in my Fast coil article on thsi web site.

Obtain a solder sucker or a desoldering gun to suck out the solder and not damage the board.

Remove LM709 the first amplifier and install an 8-pin scoket and install an NE5534, a low noise op amp.

Reduce the gain by changing the 1M feedback resistor with a 470K resistor.

Remove both compensating caps 10pf and the 3.3pf cap.

Increased C7 1000uf to a larger value like 3300uf to 4700 or some value that would fit the same footprint. Do this on other large electrolytic caps also.

Change both electrolytic caps in the +/- 5V power supply to Tantalum caps 10V about 47uf. Observe polarity!!!

Reduce the two 47 ohm resistors to about 27 ohms to provide a little more voltage at the amplifier stage.

Add a 4-pin mic jack and plug to connect a new coil. The cable strain relief comes out leaving a hole that will fit a chassis mount connector.

Only make the new coil coax cable length about 32" long so as to reduce the TX circuit capacitance.

On the 555 IC change the 1nf or 1000 pf cap to about 680 pf (use a mica capacacitor only) to increase the pulse frequency range to a max of about 10K PPS this will get your delay down as the frequency control adjusts the pulse width and delay at the same time the frequency is changed. At about 10KPPS, the delay is about 10uS.

Before you make any mods, check that the CS6PI is working. Look at the pulse on the coil connector inside the control box with your scope. The peak flyback voltage is about 80V.

Read Carl's Hammerhead construction article as the circuits operate in a similar manner using a 555 chip to produce the pulse and an NE5534A for the first amp stage.

Then make the changes one at a time and continue to verify that the CS6PI is working.

If you raise the frequency after changing the 1 nf cap and the coil stops responding using the stock coil, that is normal as you have reached the limit of the stock coil's delay range. Just reduce the frequency to mid point and it should start working again. If you go to the trouble of increasing the frequency range you should consider making a new coil to match the new lower delay range of the modified CS6PI.

With these mods, you should be able to detect a nickel at about 14".

The audio circuit in the top handle box, has a large value resistor (a few hundred ohms) to limit the audio volume to the headphone. There are some rules in Europe to protect hearing from loud noises. This has the consequence of limiting the audio sensitivity. Just visually trace out the circuit connection to the headphone jack and look for the resistor that limits the headphone volume using an ohm meter and bridge a 47 ohm resistor across it. That should allow you to have a little more audio sensitivity.

I was able to fit a 10 AA battery pack in the battery compartment sideways by obtaining longer metric screws to hold the cap on. Rechargables are rated at 1.2V each so you need 10 to look like 8 regular 1.5 V AA batteries at 12 V.

Remember, high frequency pulse induction metal detectors make up for the lower power by supplying more pulses and having the potential to sample sooner, with a lower flyback voltage, where the signal is stronger on low conductive targets like gold and nickles.

I was able to get my CS6PI to operate at about 13K PPS (Pulses Per Second) with a delay of about 7.5uS. I believe I used a 480 pf mica cap for my last mod.

The final tweak is adjusting the 1K damping resistor for the best damped signal after the preamp (observed with a scope). See the Hammerhead article as the procedure is the same.

This should get you moving in the right direction.

bbsailor

[headshed22]

Thank you both Simon Baker and bbsailor for your very informative replies to my post asking for help. It is somewhat very reassuring to receive replies from some of the more experienced members of the forum.
Although I class myself as very much a beginner there isn’t much that is discussed that I can not understand at least in basics & principle (except for maybe some of the L.R.L posts). Lol. So I fully take note and both understand & respect your reply’s Maybe not yet in practice but definitely in regards to basic electronic elements, i.e. I know what frequency, resistance, inductance are etc.

Simon, yes I like your suggestion of bread boarding new ideas, as you say they would be more prone to noise, interference, and such but it would definitely be worthwhile for testing and ‘proving’ new ideas.
I have just purchased a copy of a circuit and pcb design simulator software package with an LTSpice model simulator built in. “Circuit Wizard pro”. Not got scope just yet but one is next on my shopping list.

Bbsailor, I had read and saved your original post regarding your work on this detector, however your reply above is much more structured and informative it is a fantastic guide to what the limits are of the 6Pi and what can be reasonably achieved with it. You have my greatest respect for the work you have done on its improvement, and very much my thanks for sharing your results and information about it with me.
So going by what you both advise above a reasonable dual trace oscilloscope is very much my next priority, but then I am going to have to learn how to use it properly ha, only been a multimeter man up until now.

Maybe I will keep updating this thread with my improvements as they go along if anyone is interested in how a beginner gets on, it may be slow, but at the same time it could be interesting and probably quite funny.

Best Regards to all,
Russ.

[simonbaker]

Thank you both Simon Baker and bbsailor for your very informative replies to my post asking for help. It is somewhat very reassuring to receive replies from some of the more experienced members of the forum.
Although I class myself as very much a beginner there isn’t much that is discussed that I can not understand at least in basics & principle (except for maybe some of the L.R.L posts). Lol. So I fully take note and both understand & respect your reply’s Maybe not yet in practice but definitely in regards to basic electronic elements, i.e. I know what frequency, resistance, inductance are etc.

Simon, yes I like your suggestion of bread boarding new ideas, as you say they would be more prone to noise, interference, and such but it would definitely be worthwhile for testing and ‘proving’ new ideas.
I have just purchased a copy of a circuit and pcb design simulator software package with an LTSpice model simulator built in. “Circuit Wizard pro”. Not got scope just yet but one is next on my shopping list.

Bbsailor, I had read and saved your original post regarding your work on this detector, however your reply above is much more structured and informative it is a fantastic guide to what the limits are of the 6Pi and what can be reasonably achieved with it. You have my greatest respect for the work you have done on its improvement, and very much my thanks for sharing your results and information about it with me.
So going by what you both advise above a reasonable dual trace oscilloscope is very much my next priority, but then I am going to have to learn how to use it properly ha, only been a multimeter man up until now.

Maybe I will keep updating this thread with my improvements as they go along if anyone is interested in how a beginner gets on, it may be slow, but at the same time it could be interesting and probably quite funny.

Best Regards to all,
Russ.

Yes, keep us posted, we all learn from each other. Most anything goes it seems, even UFOs vigorously discussed, everyone speaks different dialect of english, it is entertaining to say the least, I love it and of course obsession with metal detectors is de rigeur.

Agree bbsailor reply is excellent, makes me wish I had CS6Pi to mod.

Cheers,

-SB

[headshed22]

Hi again all,
Have been busy while waiting to order my oscilloscope ready to try out the mod’s posted by bbsailor and Simonbaker above.
It seems there is a bit of interest lately on the forum regarding this detector with a few fresh posts and topics started.
By the way, I hope I am not hijacking this thread by posting here instead of starting a new one, if so please let me know.
I stripped the components from the pcb to take a couple of photographs of it for the benefit of the forum.
Also have been trying out my new pcb software, redrawing the board to post here as well. I have checked, double checked, and checked again the track connections, component layout etc. but as I am a novice at this I would appreciate any comments on my redrawn layout.
Yes bbsailor, on your advice above I have started to study Carl’s Hammerhead project and article and I do see the similar nature of both machines. It is a very good read and quite involved really, there are a lot of posts regarding it to go through and take in.
Anyways, here are the attached files all, so now I have to put it all back together ready for when I get my scope.
Take care all.
Russ.