no need to add addon to the board just use the original component marking at board
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IDX-PRO+VDI
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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 ?
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Originally posted by golfnut View Posti 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.
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Originally posted by ampirate View PostRefering 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 ?
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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
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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 :
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- 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 ...
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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)
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Originally posted by golfnut View PostI 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 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.
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Originally posted by ampirate View PostIf Input Frequency is about 6.5KHz, then I would probably aim 6.5KHz in the Integrator.
Then say : Chold=20nf and Rhold=10k for 1KHz-10KHz .
Which would give reasonable values sampled at 1KHz.
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Originally posted by ampirate View PostThe 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.
"But all signals are too small to break thru the diode" You may try an opamp presision rectifier here, elliott sound products website has good one of these"
Of course, I am probably just approaching an OpAmp Integrator Circuit anyway ...
Attached is a few Integrator Examples.
[ATTACH]30316[/ATTACH]
"" attachment wont open ""
If Input Frequency is about 6.5KHz, then I would probably aim 6.5KHz in the Integrator.
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