IDX-PRO+VDI

[CDI]

Now I only have photo without IC's. If you want better quality or with the IC's just tell me - tomorrow I'll take one. What are you looking for?

[ATTACH]38259[/ATTACH]

This is not last version. U have there 3 1n4148 zener diodes, version with only one 1n4148 has litle better disc. But u can easy modify your pcb.

[cacekspoko]

Can u make photo from top side of pcb?

Now I only have photo without IC's. If you want better quality or with the IC's just tell me - tomorrow I'll take one. What are you looking for?

[CDI]

no, I mean there is no big difference between sensitive pot on minimum and maximum even like in Eldorado.
On pin 6 U1 I have 100-150mV. What chip do you have at U3, which one do you have the best results?

For U3 i have LF347, but i bought 20 of them and changing where found one which can reach best distance. Can u make photo from top side of pcb?

[cacekspoko]

U mean unstable with pot on maximum? How much mv u have on pin 6 U1?

no, I mean there is no big difference between sensitive pot on minimum and maximum even like in Eldorado.
On pin 6 U1 I have 100-150mV. What chip do you have at U3, which one do you have the best results?

[CDI]

Now I have R24 - 1M, R25 - 1k trimpot, R26 - 100k. The problem is with P5 sensitive pot - turning it has little effect on the operation of the detector. How to improve it?

U mean unstable with pot on maximum? How much mv u have on pin 6 U1?

[cacekspoko]

Now I have R24 - 1M, R25 - 1k trimpot, R26 - 100k. The problem is with P5 sensitive pot - turning it has little effect on the operation of the detector. How to improve it?

[CDI]

10" for 16mm coin is exelent distance. Do u have 47R or 470R for R26 resistor? Delete that resistor and add small trimpot 2K to set more distance.
For R24 set 2M2 resistor.

[CDI]

Thank you. Now I have GEB working well and I noticed coil range improvment in the air test -circa 10" for the small 16mm diameter CuNi coin. Next step I will change C32 and R32 and see the results.

Another question - is the VDI works properly with that DD coil set to 12kHz TX?

Ofcourse, but i tried only arduino vdi, u can find on arduino vdi thread my sketch file where i implemented codes for several led diode's. That setup work's realy accourate with 12 khz, but u need to calibrate vdi numbers with disc pot. For example: Set disc pot to zero position and turn right where iron nail start to give numbers in range of 0 - 10.
Also, my led setup can work with or without display, just connect diodes and u have for example: red led for high conductor's, green led for medium conductor's and yellow for bad target's in range about 0 - 20.
Good luck.

[cacekspoko]

I just changed tank capacitors which goes inside search coil. Try with that setup to null, as i said, much better response for smaller items, and slightly better disc and recovery speed. Good setup if u hunt Roman field with alot of junky nail's. You can also change R32 from 220K to 100K for example if u wanna faster recovery.

Thank you. Now I have GEB working well and I noticed coil range improvment in the air test -circa 10" for the small 16mm diameter CuNi coin. Next step I will change C32 and R32 and see the results.

Another question - is the VDI works properly with that DD coil set to 12kHz TX?

[CDI]

Turns are the same like this one:

TX 35 turns 0.6
RX 260 turns 0.2

?

What about C1 220nF - @golfnut recommended 100nF for 12kHz TX. Should I change it ?

Thanks for your suggest - i'll check

I just changed tank capacitors which goes inside search coil. Try with that setup to null, as i said, much better response for smaller items, and slightly better disc and recovery speed. Good setup if u hunt Roman field with alot of junky nail's. You can also change R32 from 220K to 100K for example if u wanna faster recovery.

[cacekspoko]

I can suggest you to try with 12 khz combination if coil is not filed with epoxy yet.
Use 330N for TX and 9 - 10N for RX stage and try to null again. Has much better disc and better response to smaller coins. Good luck.

Turns are the same like this one:

TX 35 turns 0.6
RX 260 turns 0.2

?

What about C1 220nF - @golfnut recommended 100nF for 12kHz TX. Should I change it ?

Thanks for your suggest - i'll check

[Koala]

So RX coil needs correction number of winding? But what with recommended RX resonance frequency? It will be change.



Below is my TX/RX coupling

http://www.geotech1.com/forums/showthread.php?18051-IDX-PRO-VDI&p=199348#post199348

For a DD I believe. Have to admit I never check I just used the parameters posted on page one of this thread and ferrite was always rejected bang in the middle of the pot adjustment

[CDI]

I can suggest you to try with 12 khz combination if coil is not filed with epoxy yet.
Use 330N for TX and 9 - 10N for RX stage and try to null again. Has much better disc and better response to smaller coins. Good luck.

[cacekspoko]

50k is a lot of ground to control, rather 30k. Set ground control to the middle position and the selection of the reception capacity of the winding device to Achieve never seen ferrite.

So RX coil needs correction number of winding? But what with recommended RX resonance frequency? It will be change.

Sounds like the phase is too far out. Try changing the RX capacitor a little

Below is my TX/RX coupling

[Koala]

Hello,
I have problem with my IDX. I made dd27 coil:


TX 530mH 0,7 6,60kHz 14Vpp
RX 35mH 0,15 4,64kHz


TX/RX phase about 90 degrees 150-200mV


Discrimination and PP works well only the GEB has a problem. I have 50k pot for the GEB and ferrite is invisible untill I set the GEB pot to 2kom then is visible to 50kom so the regulation is very unuseful. How to set this point in the middle position of the potentiometer? I increase 220p cap to 330p, decrease it to the 100p but no change. Any ideas, help?

Sounds like the phase is too far out. Try changing the RX capacitor a little