IDX-PRO+VDI

[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.

[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/showt...348#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

[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

[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 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]

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.

[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.

[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]

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]

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]

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]

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]

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.

[CDI]

This is last update.

[cacekspoko]

So if you recommend that mod i will do it and try to change R24 but now i have to fill coil with epoxy What is the properly value of nulling? I have to to get it as low as is possible?