IDX-PRO+VDI

[ampirate]

If Input Frequency is about 6.5KHz, then I would probably aim 6.5KHz in the Integrator.

If : Chold=0.1uf=100nf and Rhold=9K giving Freq=177Hz-1.7KHz ;
Then say : Chold=20nf and Rhold=10k for 1KHz-10KHz .
Which would give reasonable values sampled at 1KHz.

[ampirate]

I tend to agree with everything you say here, the one bit that isnt great is the series diode in the drawing.
Signals < ~650mV would never be measured due to Vf on the diode
You could try an opamp sample and hold - activated by the user, during target hit with manual reset..
(one per CH)

The assumption is that the RC Hold circuit is after an OpAmp amplifying each Channel.
The Diode is needed because the Voltage would usually average to Zero between Positive and Negative Wave Peaks.

Of course, I am probably just approaching an OpAmp Integrator Circuit anyway ...

Attached is a few Integrator Examples.


If Input Frequency is about 6.5KHz, then I would probably aim 6.5KHz in the Integrator.

[golfnut]

I tend to agree with everything you say here, the one bit that isnt great is the series diode in the drawing.

Signals < ~650mV would never be measured due to Vf on the diode


You could try an opamp sample and hold - activated by the user, during target hit with manual reset..

(one per CH)

[onuba]

Arduino VDI v3 pin8 pin7 and v4 pin3 not work pin5 not work v4 pin3 pin8 parese move numbers and differentiate iron but not clear

[ampirate]

I see a lot of mixed numbers in my VDI output.

Maybe the outputs would be better buffered ? :
- Like from the OpAmp Outputs, to a Diode to a HIgh Impedence Resistor then to a Parallel small Cap and Res to Gnd ,
before feeding it into the Arduino ADC Ports ...
Something like this :
-
- Or some values, I am not sure, need to test.
Enough to pad the output Voltage average SUM into the Cap to have ready for the ADC, say for 1/100 Second Period storage time (RC=100Hz).
So, ADC input will have the Average Voltage for the last 1/100 second.

Do this, instead of taking an average of Pulses by 85 ADC Readings on the Arduino.

I think the Arduino VDI is reading Highs and Lows from the Input Wave - and getting too much random data ...

[ampirate]

VR1 = geb Balanse of land, rechaso ferrita.VR3 = for phase change

These sound useful, especially VR3 would help a lot for Tuning,
Will definately add these Mods !

- Thanks.

[golfnut]

the disc ch samples later and gets less signal thru
The geb Ch samples reasonably optimally for most alloys ( amplitude wise) and so is more prone to saturate the final stage filter/amp.

When they sturate, they take a little time to flush or clear/recoever - this is mitigated by limiiting signals to a level set by trhe diodes forward volt drop, so the amp can neve satuarate.

(Signals never crash into the rails) so recovery into the next object is good.


removing limiter ( log amp function ) will allow the phase integrity, until a large signal comes thru and the vdi No will skew as the geb ch saturates.

It may limit search speed in high trash density - try it both ways.

it will give a vdi reding to signal 30dB smaller

[onuba]

Refering to my Silverdog pcb :
[ATTACH]30288[/ATTACH]

The siverdog pcb does not include these mods below:

What is the purpose of VR2 and P6 Button mods ?

The Diodes D1 and D2 are only a Single diode on my Silverdog pcb.
Why are there 2 Diodes on the schematic mod ?

And, what is diode D3 for - which is not on Silverdog pcb either ?

Last, What are VR1 and VR3 for ?
Also, not yet added mods.
What do these calibrate ??

Could THESE Missing Part Mods - be part of the Noise issue ?

VR1 = geb Balanse of land, rechaso ferrita.VR3 = for phase change

[onuba]

Ampirate LF347 is looking down, if we read pin, 7.8. looking up they read 1.14

[ampirate]

i would go for 7,8 keep the measurement of linear signals, the vdi wont "see " small targets (same as a deus)

with 1,14 the geb on 14 is will be non linear due to diode feedback. so the integrity of the phase relation gets lost.

Would Pins 1 and 14 be usable if the Diodes were Disconnected ?

[paku]

the reason! that is NEW Board of The last version no need to add any trimpot on board just figure out you board to be stable first

[ampirate]

Refering to my Silverdog pcb :


The siverdog pcb does not include these mods below:

What is the purpose of VR2 and P6 Button mods ?

The Diodes D1 and D2 are only a Single diode on my Silverdog pcb.
Why are there 2 Diodes on the schematic mod ?

And, what is diode D3 for - which is not on Silverdog pcb either ?

Last, What are VR1 and VR3 for ?
Also, not yet added mods.
What do these calibrate ??

Could THESE Missing Part Mods - be part of the Noise issue ?

[paku]

no need to add addon to the board just use the original component marking at board

[ampirate]

I am using the Silverdog pcb.
Are there any mods on this that might help with the Noise problem ?

What is the use of VR2 and P6 ?
Should I add these to the board ?

[onuba]

i would go for 7,8 keep the measurement of linear signals, the vdi wont "see " small targets (same as a deus)

with 1,14 the geb on 14 is will be non linear due to diode feedback. so the integrity of the phase relation gets lost.

will do the connection at pin 7 and 8 of V3, Thanks golfnut