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**aft_72005** · 10-31-2008, 08:06 AM

Hi rael
It is interesting, thank you .what is performance?
Best regards.

**michael** · 10-31-2008, 08:59 AM

Hi, now you presented such info, would you please describe this MD ?and tell its' abilities and the technology it uses; BFO, VLF or PI?
Thanks in advance.

**aft_72005** · 10-31-2008, 10:11 AM

Hi michael
It is vlf type , coil ,coplanar with series resonance which produced high amplitude on
Tx coil .also uses three ppl ,………..I don’t speaking more about it .because this rael
Thread . excuse me rael .

**aft_72005** · 10-31-2008, 10:25 AM

rael,Why in this design using two xtal osc? Seem as we are be able one osc instead of two .
Best regards.

**michael** · 10-31-2008, 06:21 PM

Originally posted by aft_72005 View Post

Hi michael
It is vlf type , coil ,coplanar with series resonance which produced high amplitude on
Tx coil .also uses three ppl ,………..I don’t speaking more about it .because this rael
Thread . excuse me rael .

Hi Aft, thank you, if you know it and worked with that please describe its' power, stability, accuracy,.....
It seems Rael is not desire to reflect such things.

**rael** · 11-01-2008, 09:02 AM

Hi Aft and michael,

Exactly, GDD71-IB is VLF induction balance MD with 38 cm coil and 5kHz working frequency.
I have not experience with GDD71-IB or Thunder and can not comment them.
Using of two oscillators is designers choice. I think, one oscillator and another counter is possible.
IGDD71-IB is Thunder modification.
http://ciklon.com.ua/pix/schems/

Comment for GDD71-IB & Thunder (in russian) found at:
http://www.md4u.ru/forum/viewtopic.p...6877f6fefa5b94

Some comments from GDD71:
"Power consumption is 115mA."
"MD is very stabile and tuning is not necessary during working."
"MD work perfect with 38 cm search head."
"I find targets in depth out of reach for usual MD."
"The Temperature stability is excellent during two month testing."

"GB - phase shift ~45deg.
DISK - phase shift ~145deg.
(4046 VCO OUT pin 4) "

Regards

**michael** · 11-01-2008, 10:11 AM

Hi Rael, thank you. although I'm not electrician and don't know enough electronic, but it sounds to me the schematic is incomplete. where is coil formula and PCB layout including components on? Have you made yourself this or know anybody's made?
I ask these cos seriously want add one good/reliable VLF in my detectors collection (for some especial using

) which be worth.
so is necessary for me be assured about it. if some things are misty, avoid of wasting time or become a drifter here.
I tried the link to Russian forum found nothing useful, would you please put some founds by this MD here? with more details: target size, depth and soil condition.
Thanks in advance.

**humhum** · 11-01-2008, 01:25 PM

Hii to ALL
Thunder-3 sens depth 1E = 35cm air.

Чувствительность ( 5коп СССР воздух) 35см

GDD71-IB = ? cm.

**humhum** · 11-01-2008, 06:56 PM

Колко му е дълбочината за една монета.

**aft_72005** · 11-02-2008, 05:20 AM

Originally posted by michael View Post

Hi Aft, thank you, if you know it and worked with that please describe its' power, stability, accuracy,.....
It seems Rael is not desire to reflect such things.

Hi michael
No,I didn’t have any experience with gdd71 , my knowledge only result of
Circuit Moment study.
Best regards.

**aft_72005** · 11-02-2008, 05:34 AM

Здравейте Rael
Не мога да изтеглите gdd71.zip файл от връзките в MDF4.
Да не си като него? Можете ли да ми изпратите?
Изглежда, тъй като беше натопи следа софтуер формат. Аз като istall натопи следа в моя
Компютър.
Моят имейл: aft.72005 @ gmail.com

С най-добри пожелания.

Hi rael
I cannot download gdd71.zip file from the links at MDF4.
Are you having it ? can you send me?
Seem as it was dip trace software format . I having istall dip trace on my
Computer .
My email :[email protected]

Best regards.

**rael** · 11-02-2008, 09:09 AM

Hi,

gdd71 give next coil data :
Tx - d-38cm 105 turns 0,4 - 100nF/630V
Px - d38cm 28 turns 0,27
Rx - d19cm 220 turns 0,27 - 47nF

He not comment targets and depth in md4u.ru forum.

The big coil have bad discrimination and low sensitivity to small object.

To humhum,
GDD71-IB и Thunder имат почти еднаква аналогова част и би трябвало да имат еднаква чувствителност.
Thunder работи с 18 см бобина и има по-голяма чувствителност за малки обекти. GDD71 цели дълбочина за по-големи обекти.
Но всичко зависи най-вече от прецизно изработената търсеща бобина.

The missing diptrace file is attached.

Attached Files

GDD71-IB-METAL-DETECTOR.zip (32.9 KB, 928 views)

**aft_72005** · 11-02-2008, 09:40 AM

Hi rael
Thanking so much, but gdd71.zip at MD4U contained 1.3MB. may be cannot
Uploaded here. Please send me completed file to my mailbox.
It was also contain circuit diagram in *.dch format.
Best regards.

**humhum** · 11-02-2008, 07:34 PM

Ok Thanks.