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Offline alextt4
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« Reply #70 on: October 01, 2009, 10:55:42 am »
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i'm sorry
i dont underestand english good
i try speak to you

1. can i  use instrumentation Amp Amplifier Instead Of UA709

2. the piezo is not work

3. SPEAKER is not work.

thank you

 Smiley Smiley

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Offline goldigger
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« Reply #71 on: October 03, 2009, 02:38:46 am »
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Quote:Posted by alextt4
i'm sorry
i dont underestand english good
i try speak to you

1. can i  use instrumentation Amp Amplifier Instead Of UA709

2. the piezo is not work

3. SPEAKER is not work.

thank you

 Smiley Smiley


Eeeeewww!

Well, I cannot see why (trying to remember the circuit where the 709 is,) why you can not use an LM741 or Ne741, but not a TL071/81 as they need a split power supply for +volts and -volts. If the instrument amp is basically an op amp, it should work... a fast slew rate is good, too. The TL081, in my experience does not work with a single ended power supply where -Volts is ground. A 709 is a very old op amp that could work at radio frequencies but that is not needed here, I think the 709 has a fixed gain, so any substitution will need a resistor added, to go from the - input to the output pin, one that is variable, maybe. If the input (- input) has 10 k, use a 10k fixed resistor, in series with a 100k trim pot, this will give a gain from 1 to 11. If there already is a resistor, in the circuit (remember, I do not have the diagram,) you do nor need to add anything, just get the pin connection right and you can do that with a small header, and a socket, for the replacement chip.

Your English is not that bad, you need more vocabulary to choose from.

If you have no sound, there has to be a problem BEFORE the sound section, try setting the detector  up where you can test in the circuit and flip a  metal object by the coil. Find where the voltage changes, with the metal presence change, and follow the change through the circuit, testing with your voltmeter, until you find where the change stops, that is probably where the problem is.

Have you looked for simple things like solder blobs, on the solder side, shorting out something.... that is very common, even experts get it.  Shocked

I have looked and looked for that schematic but it has vanished! I will try to get another..... but hey, I hate this model of detector.  Grin

goldigger

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« Last Edit: October 03, 2009, 02:41:18 am by goldigger »
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Offline alextt4
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« Reply #72 on: October 03, 2009, 08:00:29 am »
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thanks goldigger  Wink

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« Reply #73 on: October 03, 2009, 08:02:17 am »
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Quote:Posted by alextt4
thanks goldigger  Wink


De nada, es mi gusto.

goldigger

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Offline erolunall
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delta  pulse
« Reply #74 on: October 07, 2009, 08:08:25 am »
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Hello

A new Pcb and part placement drawn by a Turkish forum member.

Nobody built it yet.Needed to checked for any error.
But it is looking very good.

Best Wishes
Erol
Posted on: October 07, 2009, 05:07:11 PM
Part placement

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GoldScan 4 PCB.pdf
GoldScan 4 Yerleşim Planı.pdf


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Offline alextt4
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« Reply #75 on: October 07, 2009, 11:12:46 am »
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hello goldigger
you are very good friend for me
please send me a your film to my email
you have a good day
bye bye  Kiss Kiss Kiss

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« Reply #76 on: October 09, 2009, 11:46:02 pm »
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Quote:Posted by erolunall
Hello

A new Pcb and part placement drawn by a Turkish forum member.

Nobody built it yet.Needed to checked for any error.
But it is looking very good.

Best Wishes
Erol


Goldscan was originally built as (mine) surveying equipment and used lead acid batteries because of the HUGE current consumption! It is a terrible hack!

The design has been superseded by more recent versions including one with surface mount electronics!

The complexity of the circuit is massively fault ridden in the re-engineered schematics, please see an example, below of an un-usable gain control, leaving the op amp, concerned, with a gain of one!

X marks the spot.... cut this trace OR do not install this wire!

goldigger

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« Last Edit: October 09, 2009, 11:49:06 pm by goldigger »
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Offline alextt4
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« Reply #77 on: October 14, 2009, 08:33:34 am »
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hello goldigger
can i use of AD549 Stead UA709 ?

can i use of DD coil for gold scan 4?

for circuit optimization or power boost machine what is your idea ?

please help me? Smiley

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« Reply #78 on: October 15, 2009, 11:54:50 am »
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Quote:Posted by alextt4
hello goldigger


>can i use of AD549 Stead UA709

If the pins match, why not... I do not know if you have a board, already constructed, or are building it, certainly, if you are building it, you can allow for any IC pin-out differences.

> can i use of DD coil for gold scan 4?

Since this is a pulse machine, you could use one for the transmitted pulse and one for receive, if they meet the requirement specified in the construction info.... if you have construction info. Otherwise, I am not sure of the inductance needed for the transmit.

> for circuit optimization or power boost machine what is your idea ?

Good question! From all I have read, the pulse has to be VERY short  (5 micro seconds.... which is 0.000005 seconds), this would be the only real optimization. The originator's notes say the high voltage pulse is undesired so a snubbing resistor should be included at the TX coil, probably 1k to 10k, this will control the pulse, some, and at the RX end, what ever is in the circuit, like a diode, with K to ground, holds the high voltage pulse in control, this is made up, in the op amps, so 0.7v is a lot to work with.

However, I have found some of the old circuits using a pulse as long as 35 microseconds!

It is the timing/phase that is important, not the signal strength. Some of the literature shows an iron response leading the TX pulse and a gold response lagging the TX pulse.

Honeywell has some pulse circuits, for set/reset of their magnetometer ICs, these are perfect circuits to study and may give you some ideas.... from all I have been reading, it is not a  power pulse that works,  but the charge/discharge of a capacitor through the search coil. Try their web site and look at the *set-reset* circuits for the HMC1001.

I understand that this, above, view may be contrary to the view of others, on the forum, but it is something I intend to find out if true or false! I would rather use a 2N2222 and a 2N3906, to pulse the coil, than a high current FET.... saves power, so a smaller battery would work.

What I am saying is the Honeywell reset circuits do NOT use a DC current, through the coil, instead, a capacitor is charged by a relatively low current, low power circuit and discharged though the coil, as a two direction current flow, in a high current surge, which makes the intense magnetic field, used.

How did I do.... did you understand this *lecture?*  Grin

> please help me? Smiley

I am trying, I am trying!  Shocked

goldigger

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« Reply #79 on: October 16, 2009, 10:52:06 am »
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thanks goldigger Wink


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