IDX-PRO+VDI

[Koala]

Well done yo4hfu.

Looks like you have the hang of the IDX all ready


Always nice to get some nice finds to give you confidence in your machine.

Funny thing I found with my home made coil vs a 8" concentric coil is battery life. With the factory coil I can get 30 plus hours but with my home made its around 16. I know it depends on the batteries and temperature. You can keep going after the 16 hours probably for as long as before but on loud long beeps it start to break up and the sound not as crisp as before.

[seadoggy]

Hello Geotech!

I finished IDX Pro and the results are very good for my first VLF IB detector.
For air test the 1E coin is detected at 45-47cm and 34cm at ground test with better sound for high power option (TX oscillator have full power supply from 14V battery pack). I need to make more tests in clean soil.
RX front end was replaced with LT1115 and the sensitivity increased with some centimeters. GB/DISC Filters use LF347. Voltages for operational amplifiers are filtered with 100nF + 10uF smd tantalum.
Null voltage is 500mVpp measured after RX preamplifier (U1-pin 6) and TX voltage 15,7Vpp for normal mode. Voltage across TX coil was 25,5Vpp for high power mode. For shield i use aluminum foil from RG-6 coaxial cable.
Coil type: DD 27cm
TX coil=0,62mH + 973nF; 6,5KHz
RX coil=35,5mH + 27nFll5,6nF; 4,68KHz
Now i don't remember exactly phase shift angle but is not very critical. I chose coil position for minimum rx voltage and the discrimination was ok.
The machine is stable and iron discrimination is good, only some audio cracks from rusty iron.
Also i have VDI box with PIC16F690, the indication is useful for visual discrimination .

Next device is KID FM 1 Pinpointer, good sensitivity and discrimination capability with PIC12F629.

Hello mate where you put LT1115 in place of ne5534??
Regards

[yo4hfu]

Yes, i replaced the NE5534 with LT1115.The results are better.
My PCB:

[seadoggy]

Yes, i replaced the NE5534 with LT1115.The results are better.
My PCB: [ATTACH]33518[/ATTACH]

Nice mate,did you change more componets??i dont understand where you
put smd tantalum cap,can you make better pic of your PCB mate??
Regards

[yo4hfu]

I put capacitors between +/- power supply and ground only for stability reason. Here you have some pics: PCB, PCB LT1115 detail.
SMD ceramic capacitors = 100nF
Yellow cable is + TX Oscillator for Power TX switch.

Other modification: 4066 replaced with 4016 (low leakage switch) and Sensitivity adjust simplified.

Bonus - one photo with phase shift between RX signal (U1 pin 6) and GB/DISC sampling switches: Phase Sampling
RX signal and Ground Balance signal are in quadrature.

[seadoggy]

I put capacitors between +/- power supply and ground only for stability reason. Here you have some pics: PCB, PCB LT1115 detail.
SMD ceramic capacitors = 100nF
Yellow cable is + TX Oscillator for Power TX switch.

Other modification: 4066 replaced with 4016 (low leakage switch) and Sensitivity adjust simplified.

Bonus - one photo with phase shift between RX signal (U1 pin 6) and GB/DISC sampling switches: Phase Sampling
RX signal and Ground Balance signal are in quadrature.

thx alot mate ,i what deep u got with that metod??did you try mate in ground.

[Emiliano_070]

Hello fellow just finished a IDX but unfortunately not working properly, turn the detector has not given any sign of life but to pinpoint mode works pretty well and also, change the measured integral resistors and capacitors all everything seems to be in standard .Usage TX coil -0,58mH 0, 70 wire. 0.20 RX-35,6mH wire. and I'm running out of ideas to do to work well. please if anyone has advice me say

[Koala]

Hello fellow just finished a IDX but unfortunately not working properly, turn the detector has not given any sign of life but to pinpoint mode works pretty well and also, change the measured integral resistors and capacitors all everything seems to be in standard .Usage TX coil -0,58mH 0, 70 wire. 0.20 RX-35,6mH wire. and I'm running out of ideas to do to work well. please if anyone has advice me say

Works in pinpoint so voltages should be okay

Try a large target like an aluminium can or PCB board. Try turning disc POT's both ways.

[seadoggy]

Any one get problem with IDX pro!!MPSA 13 over heat!!My idx work very well but now mpsa 13 get to hot and idx make lot of noise!!any one have idea what can be?!
Regards

[calebsone]

got it

So I finally finished vdi works too I had to hand draw the board but it still works only thing if you made the vdi too how did you adjust the trimmers on the vdi board is there any spot to look for?

[Emiliano_070]

Works in pinpoint so voltages should be okay

Try a large target like an aluminium can or PCB board. Try turning disc POT's both ways.

hello with a big can insensitivity if it works but if it works. starting from now I'll have to follow. Thank you

[Koala]

hello with a big can insensitivity if it works but if it works. starting from now I'll have to follow. Thank you

sounds like the coil if the phase is too far out then disc mode does not work correctly

or the LM393 have been known to cause disc problems

[Koala]

Any one get problem with IDX pro!!MPSA 13 over heat!!My idx work very well but now mpsa 13 get to hot and idx make lot of noise!!any one have idea what can be?!
Regards

Nothing on the board get warm let alone hot so is a miss

Board does not like the speakers to be to low an impedance the original internal speaker is 32 ohms think someone damaged the MPSA13 using a 4 ohm if my memory is correct

Also beleive someone had the MPSA13 getting hot due to a solder bridge.

Make sure you phone jack is insulated from earth as the sound uses the minus rail

[kaligula]

Can I use Garrett gtax coil at 7 khz? Is it with capacitators inside the plate and what is inductance of rx and TX?

[Emiliano_070]

sounds like the coil if the phase is too far out then disc mode does not work correctly

or the LM393 have been known to cause disc problems

.hello the problem is solved by changing the LM393, thanks for your cooperation, lack of proper cable being'm with these two questions, some help I could do, thanks