Whites Surf PI schematic

[cordius]

Does anyone know the correct inductance and resistance values or surfmaster coil?
Regards
Nelson

350uH
3,3 ohm

[nelson]

Why you said not to work with TIP32C?
What are the diferences?
My surfmaster is working very stable, buy sensitivity still poor, a 24mm in diameter coin is just detected at 14 to 15 cms. The coil was made from 0,25 mm wire, and the target selected was a 24mm copper coin, here are my expirencies:

DIMETER TURNS WIRE INDUCTANCE RESISTANCE RESULTS
21 19 0,25 279,8 uH 5,2 16 cms
21 20 0,25 313,7 uH 5,3 13 cms
21 22 0,25 343,2 uH 6,5 14 cms
21 23 0,25 372,4 uH 6,0 14 cms
21 24 0,25 406,5 uH 6,1 14 cms
21 26 0,25 498,8 uH 6,8 14 cms
21 27 0,25 538,3 uH 7,0 15 cms
21 28 0,25 575,8 uH 7,0 16 cms
21 29 0,25 617,4 uH 7,6 14 cms
21 30 0,25 664,4 uH 7,6 13 cms

I tried to set margin on this chart, but was imposible. Anyway to read it, you should follow the correct text and number order or get the file below

I hope this can help someone.
Measurements were made with Atlas LCR, model LCR40, that is very accurate.
The detector hold the same conditions for al test.
I forgot, i didn´t find IRF9640, so i used IRF 9630.Could this affect power or sensitivity?

Regards

Nelson

No need transformer. Dump resistor is 390 ohm using IRF9640. Don't work with TIP32.

[hobbes_lives]

Does anyone know the correct inductance and resistance values or surfmaster coil?
Regards
Nelson

I believe this is accurate:

http://www.geotech1.com/cgi-bin/page...oils/index.dat

[nelson]

Than´s Cordius.
Kind regards
Nelson

350uH
3,3 ohm

[cordius]

My experience with TIP32 it is very very hot and surfmaster dont' work.
IRF9640 is good for this project.
No good 14-15 cm for 24 mm coins.
my surfmaster detect 20 cent euro at 23 cm in air and my mobile phone at 37 cm.

[Eugene52]

Surf PI schematic

I believe this is accurate:

http://www.geotech1.com/cgi-bin/page...oils/index.dat

Thank-You hobbes_lives , Definitely worth saving !! Best collection of search-coil Data I have seen on this forum , so far !!.......Thanks...........Eugene52

[nelson]

Thank´s hobbes.
This is diferent from the data post by Cordius.
But anyway i´ll experimet first with Cordius data.
Thanks
Nelson

I believe this is accurate:

http://www.geotech1.com/cgi-bin/page...oils/index.dat

[nelson]

Ok, now can you tell me how is the speed detection, cause today i had made some experiments with surfmaster. When i pass fast from side to side f the coil a 22 cms copper coin, this is detected btw 13 to 15 cms maximun. But when i pass the coin from side to side slowly, the coin is detected at 25 to 28 cms. I this normal?
I also noticed that the threshold on a few settings sound with an oscilating tone, like when you detect an object.
Thanks
Nelson

My experience with TIP32 it is very very hot and surfmaster dont' work.
IRF9640 is good for this project.
No good 14-15 cm for 24 mm coins.
my surfmaster detect 20 cent euro at 23 cm in air and my mobile phone at 37 cm.

[nelson]

Ok, now can you tell me how is the speed detection, cause today i had made some experiments with surfmaster. When i pass fast from side to side f the coil a 22 cms copper coin, this is detected btw 13 to 15 cms maximun. But when i pass the coin from side to side slowly, the coin is detected at 25 to 28 cms. I this normal?
I also noticed that the threshold on a few settings sound with an oscilating tone, like when you detect an object.
Thanks
Nelson

Ok, now can you tell me how is the speed detection, cause today i had made some experiments with surfmaster. When i pass fast from side to side f the coil a 22 cms copper coin, this is detected btw 13 to 15 cms maximun. But when i pass the coin from side to side slowly, the coin is detected at 25 to 28 cms. I this normal?
I also noticed that the threshold on a few settings sound with an oscilating tone, like when you detect an object.
Thanks
Nelson

[1843]

Ok, now can you tell me how is the speed detection, cause today i had made some experiments with surfmaster. When i pass fast from side to side f the coil a 22 cms copper coin, this is detected btw 13 to 15 cms maximun. But when i pass the coin from side to side slowly, the coin is detected at 25 to 28 cms. I this normal?
I also noticed that the threshold on a few settings sound with an oscilating tone, like when you detect an object.
Thanks
Nelson

It's normal... if you pass the coin faster, detection range becomes less. Because less signal is obtained by the PI.

Regards,
1843

[nelson]

Thanks 1843, so searching must be at slow speed.
Kind regards
Nelson
Santiago, CHILE

It's normal... if you pass the coin faster, detection range becomes less. Because less signal is obtained by the PI.

Regards,
1843

[hobbes_lives]

Ok, now can you tell me how is the speed detection, cause today i had made some experiments with surfmaster. When i pass fast from side to side f the coil a 22 cms copper coin, this is detected btw 13 to 15 cms maximun. But when i pass the coin from side to side slowly, the coin is detected at 25 to 28 cms. I this normal?

It depends on what you're calling fast vs slow. The Surfmaster is a fast sweep machine. The instruction manual states that you should use a sweep speed between 3 to 5 feet per second. This may vary somewhat, depending on the coil size that you built, but a relatively fast sweep should be fine. If you sweep too slow, the S.A.T. circuitry will adjust to the target signal, so you will lose sensitivity in that case. It sounds like something is amiss, unless you are sweeping extremely fast.

I also noticed that the threshold on a few settings sound with an oscilating tone, like when you detect an object.

At certain gain and threshold levels, you can hear an oscillating sound. I like to call it the "angry bee" sound. If you are testing indoors, or around any power lines, you will definitely pick up 60Hz (or 50Hz) interference as well.

Thanks 1843, so searching must be at slow speed.

Nope, as mentioned above, the Surfmaster series can be swept at a pretty fast pace.

[nelson]

Thanks hobbes.
Now i understad much better the circuit. I also download surf pi manual and 3 videos from youtube, that explain vary well how the circuit works.
Also, have you know anything about discrimination on this machine?
Kind regards
Nelson

It depends on what you're calling fast vs slow. The Surfmaster is a fast sweep machine. The instruction manual states that you should use a sweep speed between 3 to 5 feet per second. This may vary somewhat, depending on the coil size that you built, but a relatively fast sweep should be fine. If you sweep too slow, the S.A.T. circuitry will adjust to the target signal, so you will lose sensitivity in that case. It sounds like something is amiss, unless you are sweeping extremely fast.



At certain gain and threshold levels, you can hear an oscillating sound. I like to call it the "angry bee" sound. If you are testing indoors, or around any power lines, you will definitely pick up 60Hz (or 50Hz) interference as well.



Nope, as mentioned above, the Surfmaster series can be swept at a pretty fast pace.

[hobbes_lives]

Also, have you know anything about discrimination on this machine?

Nelson, like most PI detectors, the Surfmaster does not have any discrimination. It detects all metal.

With that being said, after you use the machine for a while, you can start to recognize some common junk items by the sound they make. For example, nails, bobby pins and pieces of wire make a WOW-WOW sound as you pass over each end of the item. With practice, you can start to recognize bottlecaps too. However, since I hunt the beach, and the digging is easy, I just as well dig it all up to make sure I'm not missing any goodies.

[nelson]

Thank´s hobbes.
I ask this cause i saw a mod for surfmaster, that adds a 100K pot for discrimination.
Now i m working on the housing for surfmaster, so later i hope i ll have the time to know it better.
Finaly, do you know if Surfmaster PI Pro is the same has Surfmaster Dual Field?
Regards
Nelson

Nelson, like most PI detectors, the Surfmaster does not have any discrimination. It detects all metal.

With that being said, after you use the machine for a while, you can start to recognize some common junk items by the sound they make. For example, nails, bobby pins and pieces of wire make a WOW-WOW sound as you pass over each end of the item. With practice, you can start to recognize bottlecaps too. However, since I hunt the beach, and the digging is easy, I just as well dig it all up to make sure I'm not missing any goodies.