GOLDSCAN 5 SCHEMATIC QUESTION

[daverave]

orbit do you know how whites got the audio threshold so stable in the TDI sl version even at max sens setting ???

[Qiaozhi]

i have modified two of my detectors to work down to 8 uS and work fine on the dry sand but on the wet sand too much chatter and thats why i wondered if a bi polar coil drive would eliminate the chatter at low delays...so is it only on inland field sites that the bi polar coil system will eliminate the ferrous ground effect ???

If you're lucky you may be able to set the sample delay between 10us and 15us, but in general (for wet sand) it is normal to use a 15us sample delay.
What you're referring to for inland sites is called viscous remanence magnetization (VRM). Carl should be able to give you a more detailed explanation on this.

[Orbit]

orbit do you know how whites got the audio threshold so stable in the TDI sl version even at max sens setting ???

Yes I know but I think it's TDI still a commercial device , although there are some other ways that the threshold of the tone be silky without ipon effect,I do it on my analog detector , moreover it can make even less noise than the original TDI SL..

[6666]

Hello Qiaozhi....when you say a bi polar coil drive minimizes the problem of magnetizig the ground so does that work the same for wet sand and does that allow the use of lower delays without chatter on the wet sand...also does anyone have a diagram of a bi polar coil drive that can be used for any pulse detector.

There was some work done on this BP design
https://www.geotech1.com/forums/show...ighlight=af108
https://www.geotech1.com/forums/show...ighlight=af108

[daverave]

someone told me the whites tdi sl has a fake threshold that gives a more stable threshold

[daverave]

on youtube some claim they can use a delay of say 7 uS on wet sand using the fisher AQ which has a bi polar coil drive from what i see...so im a bit confused

[Qiaozhi]

on youtube some claim they can use a delay of say 7 uS on wet sand using the fisher AQ which has a bi polar coil drive from what i see...so im a bit confused

Bipolar pulsing can only ignore signals which have the same polarity during both positive and negative cycles. The signal from wet salty sand changes polarity during each pulse.

I think I've found the youtube video you're referring to. On the front panel of the Fisher AQ there is a control marked "Reject" which is labelled from 1 to 12, and I notice that the default setting is 6. I suspect these numbers do not refer to the actual main sample delay.

[daverave]

Hello Qiaozhi....its just all confusing as i asked someone on youtube who was using a fisher AQ about the 7 uS delay setting and they told me they could use the 7 uS setting on wet sand without chatter but they said in the surf if the coil is swept in the waves then the detector will chatter

[Qiaozhi]

Hello Qiaozhi....its just all confusing as i asked someone on youtube who was using a fisher AQ about the 7 uS delay setting and they told me they could use the 7 uS setting on wet sand without chatter but they said in the surf if the coil is swept in the waves then the detector will chatter

There's nothing on the front panel that indicates micro-seconds.

[dbanner]

Perhaps the user manual can shed light, although I'm skeptical about any manual making reference to "microseconds" when dealing with devices meant for public consumption.

[Orbit]

someone told me the whites tdi sl has a fake threshold that gives a more stable threshold

No it's not a fake threshold , the threshold is real!

[green]

There's nothing on the front panel that indicates micro-seconds.

https://www.geotech1.com/forums/atta...7&d=1606133374

Wondering if pot(lower right)isn't labeled in micro seconds

[Altra]

In the sale brochure it claims "as low as 7us". I recall the designer stating that careful construction of the coil and digital processing allowed for short delays in wet salt. Also the AQ is not bipolar, Tartar said he has one in the works. Carl could clear all this up.

First post in the link has a sales brochure

https://www.detectorprospector.com/f...l-information/

[Carl-NC]

someone told me the whites tdi sl has a fake threshold that gives a more stable threshold

No, the threshold is real. I think the improved stability was largely due to a better layout and more attention to detail. The Impulse AQ is even better than the SL, again largely for the same reasons.

on youtube some claim they can use a delay of say 7 uS on wet sand using the fisher AQ which has a bi polar coil drive from what i see...so im a bit confused

The AQ is not bipolar.

Hello Qiaozhi....its just all confusing as i asked someone on youtube who was using a fisher AQ about the 7 uS delay setting and they told me they could use the 7 uS setting on wet sand without chatter but they said in the surf if the coil is swept in the waves then the detector will chatter

I have also used the AQ in wet salt sand at 7us. It takes a lot of care in how you swing the coil. In the surf I got some noise but I could still hunt through it, although 8-8.5us was a better setting.

There's nothing on the front panel that indicates micro-seconds.

The pulse delay (7-11.5) is in microseconds. The iron reject is just an arbitrary range, is is akin to the GB control on a TDI but used in a slightly different way.

[dbanner]

Well there you have it, clear as a midsummer day.