IDX-PRO+VDI

[Koala]

Is there an easy way to tell if the batteries are getting low when out in the field?

[kt315]

schematic

[ossamaussama]

i found that TL074 or TL084 can replace LF347

but i don't know if LF357 can replace ne5534?

[Davor]

But it does affect threshold and volume in active state.

[kt315]

The PP channel is always on, it cant be shut off.

you mistake... in disc mode PP channel is NOT effecting. do you SEE R36 100kOhm there?? (100 KILO OHMS!) a signal from PP channel does NOT go on output while comparators would be turned UP - !

[golfnut]

You got me with the op amp description it should be LF not LM...




In DISC mode if you scope U5 pin7 and adjust VR4 it raises the DC level on pin7 from a minus to plus volts.

This has the effect of biasing the audio closer to conduction.


In use, you get louder audio in Disc mode. As a consequence you loose some dynamic range on the audio, so depth perception reduces as mentioned.




The PP channel is always on, it cant be shut off.


The gain of the PP Ch is lower and contributes little or no signal in Disc mode (probably just some unwanted noise).

It is the Disc and Geb Channels which are isolated and contribute nothing when in PP mode - as the cmos switch opens via the PP switch.

In PP mode, VR4 needs to be raised to just below the point of audio tone when OFF your target. In this condition the gain of U5 and its DC output level are raised.

S

[Koala]

kt315 I have a silverdog board and when I turn the threshold up the Disc tone is louder and a slight increase in depth but loose some of the linear sound for the depth. Don't know why?

[kt315]

...

[ossamaussama]

I believe you can expect discrimination to work as well.
In order to squeeze all there is from 2box principle, a preamp should be mounted inside or near the Rx probe so that Tx noise can't enter via capacitive coupling. Even a wireless link could do.

IMHO what makes 2box better than other detection principles is that a Tx illuminates targets more evenly than any planar Rx/Tx probes. In this arrangement a dynamic range at which targets appear in Rx front end is compressed against the dynamic range of Pi or IB detectors. This means that targets near the surface will produce less response with 2box than other detectors, while deep targets will respond more or less the same. This is also true for near surface ground noise, and together with more amplification room this increases detection depth. In case of maghemites baked by bush fires that tend to be concentrated at soil surface, and is difficult to balance - the advantage is quite obvious.

Small target detection and pinpointing could be improved by favourable Rx coils geometry. All in all - it all seem very promising.

that true
i have pulse induction machine and with 1 frame it cannot detect thin AL foil ,pulse induction is not sensitive to gold as VLF

i have seen deep VLF machine with 45 cm coil reach 1.7 meter! for 0.5 meter box object



any one can do pcb for tm808?

[Davor]

I believe you can expect discrimination to work as well.
In order to squeeze all there is from 2box principle, a preamp should be mounted inside or near the Rx probe so that Tx noise can't enter via capacitive coupling. Even a wireless link could do.

IMHO what makes 2box better than other detection principles is that a Tx illuminates targets more evenly than any planar Rx/Tx probes. In this arrangement a dynamic range at which targets appear in Rx front end is compressed against the dynamic range of Pi or IB detectors. This means that targets near the surface will produce less response with 2box than other detectors, while deep targets will respond more or less the same. This is also true for near surface ground noise, and together with more amplification room this increases detection depth. In case of maghemites baked by bush fires that tend to be concentrated at soil surface, and is difficult to balance - the advantage is quite obvious.

Small target detection and pinpointing could be improved by favourable Rx coils geometry. All in all - it all seem very promising.

[ossamaussama]

[ossamaussama]

i think idx can be modified to work as 2box in non discrimination mode and modify the all metal to be non motion (static)

also replace some lm358 with better opamp such tl072 or tl082

i will do some experiments as i get magmatic wire
2 box is better for gold detection than pi machine

[Davor]

my friend davor say 1or2meter and i think it can not the max depth for idx.

Once you asked me about achieving large depths with very large coils and IDX. I told you that these depths are achievable with some PI machines and extremely large coils (no discrimination) and also with 2box devices - not IDX as it is.

I also think IDX and other IB devices could be rearranged to work as 2box devices.

[golfnut]

I know some people have a mare making this unit.

Hope this drawing helps.



S

[mohandes]

hi anyone know about the max depth can detect under the ground?
my friend davor say 1or2meter and i think it can not the max depth for idx.
regards