GOLDSCAN 5 SCHEMATIC QUESTION

[Idefix]

Hi,
To Geo : the photo is with too low definition to see the value of smd resistor.
So if you can make a more close picture to the board, it will be better.

Hi Geo, Have you had oportunity to take some more pictures?

[6666]

There is more version ,I'm interested in how much noise there is ,on all metals and how much profit the GEB ??Gabi and Jose can see a video clip ?? If Altra can put the video its TDI proto ?!

I noticed that the differential integrator in the GS 4 application generate noise as well as the synchronization cd 4538 ! I think that's the main reason among other things applied by mcu as well as 4053 by TDI SL !


https://www.youtube.com/watch?v=dV-3yKez6YY My version 1.0 ]http://tinypic.com/r/2dbm06f/9[ATTACH]41096[/ATTACH]

Is it possible to get a higher resolution picture of your circuit please, when I zoom in to read circuit values it pixilates too much, thanks.

[Altra]

Idefix

Which photo? My board has a NE5534 and a AD8055. The second photo was not my board it was from this forum which showed a NE5532 and Geo clarified that a NE5534 was hidden under the wires

[dbanner]

Idefix

Which photo? My board has a NE5534 and a AD8055. The second photo was not my board it was from this forum which showed a NE5532 and Geo clarified that a NE5534 was hidden under the wires

Does this imply an additional preamp stage?

[Altra]

No, I think they may have changed to single capacitor integrators. See the SD2000 schematic. Differential integrators need matched caps and resistors, so it's easier to mass produce a detector using single cap integrators.

[Idefix]

Idefix

Which photo? My board has a NE5534 and a AD8055. The second photo was not my board it was from this forum which showed a NE5532 and Geo clarified that a NE5534 was hidden under the wires

Altra, the photo in post #222.
The marks on the first preamp IC are not very clear.

[Orbit]

I think next ..The first operational amplifier ne 5534 has a very small gain double operational amplifier ne 5532 all metal channel there are, say, reinforcements from 500 x , while golden channel other half ne 5532 we amplify 1000 x and then, on the channel aplly filter time we get more gain with less noise ! That's my idea noise reduction !The amplification of operational amplifiers is arbitrary !

[Idefix]

Hi,
As I understand, there were the TDI, and the Goldscan 5. After, merging the knowhow from those two, the TDI Pro was born, with all the improvments , and sometimes some compromise.
So I think the TDI pro contains the last evolutions to be followed.

[Altra]

Here is a preamp which would feed single cap integrators from one of my builds. Change the AD8055 to 1/2 NE5532 and it may be what Geo's TDI preamp configuration looks like? Some good photos would tell.

[Orbit]

Here is a preamp which would feed single cap integrators from one of my builds. Change the AD8055 to 1/2 NE5532 and it may be what Geo's TDI preamp configuration looks like? Some good photos would tell.

Also i think yes! !

[dbanner]

No, I think they may have changed to single capacitor integrators. See the SD2000 schematic. Differential integrators need matched caps and resistors, so it's easier to mass produce a detector using single cap integrators.

i think i see matching caps at integrators on sd2000schematic? can you expand a bit on your explanation please.

[Altra]

i think i see matching caps at integrators on sd2000schematic? can you expand a bit on your explanation please.

By "Matching" we mean value matching. A typical capacitor may be rated at +/-5% of marked value. Now we take a bag of 100 and measure the capacitance of each. It is probable that some capacitors from the bag could be as much as 10% apart in value. Say we test a batch of 470nf. +5% would be 493.5nf, -5% would be 446.5nf these two have a 47nf difference. For our differential integrators to balance the RC time constants need to be equal between the inputs and channels. So out of the bag we want to pick 4 capacitors that are within say 1% or less of equal value and we use 1% tolerance resistors. Most hobby builders can get away with broader tolerances. But if you are building a 100 detectors on an assembly line and want the ground balance or disc control to react the same for each unit consistently you need to use "matched" components. In metal detectors, differential integrators and dual channel differentiators are circuits to be matched.

[Geo]

Here is a preamp which would feed single cap integrators from one of my builds. Change the AD8055 to 1/2 NE5532 and it may be what Geo's TDI preamp configuration looks like? Some good photos would tell.

It seems good. Connect a resistance between positiveinput of U2a and earth.

[Geo]

Hi Geo, Have you had oportunity to take some more pictures?

Not now. Maybe after 10...15 dayw if will remember me again.

[dbanner]

By "Matching" we mean value matching. A typical capacitor may be rated at +/-5% of marked value. Now we take a bag of 100 and measure the capacitance of each. It is probable that some capacitors from the bag could be as much as 10% apart in value. Say we test a batch of 470nf. +5% would be 493.5nf, -5% would be 446.5nf these two have a 47nf difference. For our differential integrators to balance the RC time constants need to be equal between the inputs and channels. So out of the bag we want to pick 4 capacitors that are within say 1% or less of equal value and we use 1% tolerance resistors. Most hobby builders can get away with broader tolerances. But if you are building a 100 detectors on an assembly line and want the ground balance or disc control to react the same for each unit consistently you need to use "matched" components. In metal detectors, differential integrators and dual channel differentiators are circuits to be matched.

Yes, i understand "matching pairs", but can you show me single cap integrator example on sd2000 schematic?