Delta Pulse

[ivconic]

!?

Forgot to post photo!?

[Max]

After 10 Delta Pulses i have to admit still dont know
everything about PI's..!?
Nothing to do these days, it is kind a monotonous here,
so i decided to make small coil for DP.
I used datas from Hammerhead project:
20cm diamm. wire 0.45mm 26 windings...
Finally resistance is 1.5 ohms.
Also Faraday cage applied (for the first time) in manner
to check this coil on higher frequencies also.
Since reistance is to low i expected fet to become very hot
in no time. I didnt used serial resistance, just waited to
see what's gonna happen...
And nothing happened???? Detector is working good, fet is
cool ???? After 20 minutes still cool???
Oh, yes, i already put heatsink, but small one, just as
"ornament" cose previously i ran this DP on low frequency
with 4-6 ohms coil resistances, so heatsink was needless
at the time...
Still, fet is cool, heatsink also???
I am confused! Now i do not understand this?
I adjusted all pots here and there, made all combinations
and waited fet to become hot - without success!?

1.5cm bronze coin detects at 25cm distance, very sharp!
1l paint can detects at 80cm sharp and at 1 meter with variations in
audio...
Small iron plyers detecting at 50cm distance....

Not so bad at all, considering size of a coil - just 20cm...

"Reject" pot. now working very noticeable as "Disc" on VLF's, but
oposite;
-When "Reject" low, DP detects all sort of metals same,
-"Reject" on "3" , DP stop detecting Al,Foils,some coins
-"Reject" on "6" , DP detects only iron, but very good!

What is this? Sort of discrimination?
Can anybody check this on other machine, i would like to
see some comparsions...


P.S.
I forgot, freq. is 270Hz with this setup...

Hi ivconic,
"freq. is 270Hz with this setup" ok, what's TX on time ?... it's the other key factor that determines consumption... and Vcc value is another one, and then you must consider inductance/resistance and then calculate the peak current (when your fet switch-off happen) and also average power of one cycle using integral of charge function of inductor...

Another thing that's important to notice if there will be too hot running on fet is its breakdown voltage and ...cause at breakdown, during switch-off, your fet must dissipate energy due to collapse of magnetic field, cause by Lenz law you coil store this energy:

|e| = |L* di/dt|

High breakdown voltage mean that your fet "opens" before of small breakdown devices (e.g. BUZ11)... then the eccess energy goes at ringing dump at dumping resistor (that become sometimes more warm than fet!).
And , of course clamping diode that suffer forward conduction during switch-off.

I had a trouble on XR-71 due to these facts... then have to change BUZ11, cause have it warm too much (freq. 400+ Hz), I've used there with an IRF740 (400 volt breakdown voltage!)... even if so I have more Rds on it remains cool (and now is big dumping resistor that dissipate big fraction of energy)!!!

Best regards,
Max

[Geo]

Hi All .
First for Max. I work my DP at 100 to 400Hz. 400Hz is better because it has better response (at 100 hz i must move slowly the coil if the signal is low otherway i lose the object). The clocking is the same at 100 or 400 Hz. Yesterday i changed the first delay from 30us to 12us. Results....... very bad depth..... why????? i had not time to check it with oscilloscope. I believe that the problem is the coil (maybe it can't go to low). I want to minimise the max delays time so to can increase the freq to 800.... 1000 Hz for small objects detecting.
Now to Ivica.
How and Where are you. I have long time to write you. Of course i am very busy this time and i didn't made a tesoro GS . What about 1266 ?
Now for DP. What are you mean reject? is the first delay Tr4 or the second delay Tr5. If it is the 1st delay then yes if we play with it we can reject some objects. At my detector i have the best results with the potentiometer about short 30....40us. The sensitivity is about the same, max 30cm for 2 euro or 1/2 euro with coil 25 cm 1000uH. With lower inductance i have a little better results but it needs lower dumper (1k/1W now i have 2k2, 1/4w) and is not so stable.
I forgot .... with delay to 80us you can reject the ceramics.
When i will finish the works (maybe on October) i program to construct Barracuda..... 1266 ........ and GS4. IT IS OK TO SPENT MY TIME ON WINTER.
Best Regards

[ivconic]

...

I can suggest you only GS4 to make....others forget...Not worth!
But you must have accurate schematic and pcb for GS4. As i heard, those posted here are not accurate!? Not sure, but heard that way....I would like to make GS4 also, but do not want to waste my time with faked schematic and pcb...Maybe you can help?

About DP. Aside other things, only thing which interesting me is fact that fet is very cool with 1.5 ohms coil?????
In the past i have a lot of problems with larger coils under 4 ohms...Fet was very hot than?

Best regards!

[Geo]

I believe that a 1266 is a very good and easy detectorwith better sens and discrimination than Tesoro, so i will give it a try. Now about GS4 as i see it will be a normal project if i will use 2 or 3 pcbs as sandwitch. DP is very good and stable but i want to do it a little better at small objects with small coil so a switch to small or big coil and it is OK
My Regards

[1843]

Hi Geo,
If you want make DP sensitive to small objects, change C21 with a 4.7uF or so.
Regards

[ivconic]

..

"I believe that a 1266 is a very good and easy detectorwith better sens and discrimination than Tesoro"

Geo i had 1266. still have it one of my friend from "company". Yes it is very good detector for coins mostly....but i managed that my TGS is much,much better now from 1266....That's why i suggest you to make TGS not 1266.
In TGS design you dont have any "critical" component, in 1266 you have transformer,quartz and funny pcb's....
But as you wish, i wish you success anyway...Keep me imformed about progress.
Regards!

[Max]

Hi All .
First for Max. I work my DP at 100 to 400Hz. 400Hz is better because it has better response (at 100 hz i must move slowly the coil if the signal is low otherway i lose the object). The clocking is the same at 100 or 400 Hz. Yesterday i changed the first delay from 30us to 12us. Results....... very bad depth..... why????? i had not time to check it with oscilloscope. I believe that the problem is the coil (maybe it can't go to low). I want to minimise the max delays time so to can increase the freq to 800.... 1000 Hz for small objects detecting.
Now to Ivica.
How and Where are you. I have long time to write you. Of course i am very busy this time and i didn't made a tesoro GS . What about 1266 ?
Now for DP. What are you mean reject? is the first delay Tr4 or the second delay Tr5. If it is the 1st delay then yes if we play with it we can reject some objects. At my detector i have the best results with the potentiometer about short 30....40us. The sensitivity is about the same, max 30cm for 2 euro or 1/2 euro with coil 25 cm 1000uH. With lower inductance i have a little better results but it needs lower dumper (1k/1W now i have 2k2, 1/4w) and is not so stable.
I forgot .... with delay to 80us you can reject the ceramics.
When i will finish the works (maybe on October) i program to construct Barracuda..... 1266 ........ and GS4. IT IS OK TO SPENT MY TIME ON WINTER.
Best Regards

Hi Geo,
if decreasing delay you lose performance you have maybe an overshot due to coil shield. Happened to me. Solved making coil as BBsailor described.

About PI to make I suggest GS4 too. It's a beast, belive me... but also on consumption side... anyway it's a very good PI and good to find small things at depth with just a 8'' coil. But be aware of bricks ! It's a nightmare when bricks are there... cannot use it.

I swear that Alexis' schematic is OK in everything now. There were few errors related to 2 fets connections, and other small things that were no good. But I've built and works perfectly and mods. are in last posted stuff. Find it.
Also I've made a thread where posted about progresses in tuning etc.

Unfortunately, I haven't a real PCB for it, cause decided to make in separate modules (proto boards) then connecting them. At the end I had incredible size for main unit... something like 30x20x8 cm black-box. There are lot of tricks and traps in GS4... expecially tuning is not easy and require much luck. It's incredible machine for beach hunting! If you get it work...

Best regards,
Max

[Geo]

Hi Geo,
If you want make DP sensitive to small objects, change C21 with a 4.7uF or so.
Regards

Hi 1843. I will try it but another way is to put a potentiometer and a switch as it is the XR71p (for critical manual tune). But why not to try your "capacitor solution".
Regards

[Geo]

Geo i had 1266. still have it one of my friend from "company". Yes it is very good detector for coins mostly....but i managed that my TGS is much,much better now from 1266....That's why i suggest you to make TGS not 1266.
In TGS design you dont have any "critical" component, in 1266 you have transformer,quartz and funny pcb's....
But as you wish, i wish you success anyway...Keep me imformed about progress.
Regards!

Hi Ivica . About "1266 critical components" you have right, but 1266 is more sensitive with standart coils. BUT you know me..... i like only to construct detectors...... not to go for theature finding. So ........
Regards

Ohhh i forgot Max. Hi Max . Yes i like GS4. Maybe is the best PI detector for small objects so i will try to construct it. I an not afraid........ i will make it ot work perfect for me. I will try to design 2 or 3 pcbs for it and so to be more easy to work without selfoscillations or ....... . All the GS4 in one pcb is more difficult and critical ....... , especially for me and for hobby .
Anyway my regards

[nelson]

Hi, i was thinking on rebuild my Delta Pulse, but with one side pcb, so if anyone know if there are any one side pcb, let me know. This cause i can{t find doble side pcb here, my actual DP was build on a one side pcb with jumpers, so i ll have to check it again, cause DP is not working.

Regards
Nelson

my little deltapulse project

[1843]

Hi, i was thinking on rebuild my Delta Pulse, but with one side pcb, so if anyone know if there are any one side pcb, let me know. This cause i can{t find doble side pcb here, my actual DP was build on a one side pcb with jumpers, so i ll have to check it again, cause DP is not working.

Regards
Nelson

Hi Nelson,

Why do you don't make Gary's PI??? It is so stable!!!

Delta Pulse is not an easy project and not recommend for beginners.

Regards

[nelson]

Hi 1843.
I had made delta pulse, but with one side pcb, so i want to finish it first.
Anyway, i have almost all componets to build Gary pulse induction MD. I have heard that this is a good detector too.
I also have made two clone pi MD with success, bust has all my detectors i know i fail with coils. Alls are working good, but i recognize that they can go deeper if i try to build good coils.
Have you made Gary PI?
If so, how was your expirence with it?
I m looking for a good machine to get gold nuggets with it.
My Tesoro Golden Sabre is working good by now, so after i finish a few coils, i ll try to build one to detect gold nuggets. But first i need to get more expirence with coils constructios, before i get into gold nuggets.
I also have heard that Gary PI MD can get nuggets at about 2 inches.
Regards

Nelson

Hi Nelson,

Why do you don't make Gary's PI??? It is so stable!!!

Delta Pulse is not an easy project and not recommend for beginners.

Regards

[Geo]

Hi Nelson .
1. I never saw a one side pcb for DeltaPulse.
2. DeltaPulse is not good for gold nuggets
3.You must use a detector with delay <15us maybe <10us. So Hammerhead (i think that you can order the pcb from Carl) or Goldscan4 (problem with pcb) are suitable for you
Regards

[nelson]

You are right Geo. My pcb is a one side with lots of jumpers on it to configure the original board, but it must be some errors on connectios, cause the detector is not working stable, so i have to recheck the board again.
Thanks and regards

Nelson

Hi Nelson .
1. I never saw a one side pcb for DeltaPulse.
2. DeltaPulse is not good for gold nuggets
3.You must use a detector with delay <15us maybe <10us. So Hammerhead (i think that you can order the pcb from Carl) or Goldscan4 (problem with pcb) are suitable for you
Regards