IDX-PRO+VDI

[Koala]

I did not add the decoupler cap. Where should I placw this ?
Silverdog helped me out with the rx cap I am now getting clear beep at 30 cm on the speaker (16 ohm).
I will keep trying different caps to see if I can improve on this result.

Excellent looks like things are moving in the right direction and it's just the coil that need dialing in. Now you have added a decoupling cap is everything now running cold.

[gtdavid]

No I have disconnected the 12v as I do not know where to place the decoupling cap can you please fill me in

[gtdavid]

This is what I did

[golfnut]

I cut the 8v line where you did .

I do not have diode.



The decoupler is to help strip ac tx signal fron the DC supply line. It will not alter the current flow thru the transistor.
If yous is running hot it will run hot with the cap too.

I would say as you have it is as good as they left the factory.

I mentioned earlier in the post to try different Rx caps to boost your sens - looks like you did that now.

well done

S

[ossamaussama]

please help me
any another way to discriminate withhout VDI , 2 TONE FOR EXAMPLE

[gtdavid]

Had any one came up with a analog vdi for this unit I love having the old needle
I am going to put this in a metal case should I earth the case out?
And should the bord mounts be plastic as the pcb mount holes are not -v ?

[golfnut]

Had any one came up with a analog vdi for this unit I love having the old needle
I am going to put this in a metal case should I earth the case out?
And should the bord mounts be plastic as the pcb mount holes are not -v ?

Well spotted - I think some people miss this detail.

I have my metal box at the +4v potential which is ground in the unit.


Be careful with the metal lockring of the audio jack socket - this is gnd and the audio ground is battery -ve terminal and NOT the local pcb gnd (which as yuo said is +4v wrt to batt -ve) So I use an oversize hole in the front panel with clearance to the socket lockring.

The audio jack itself I mounted on bare fibreglass pcb and glued it to the reverse side of the front panel.

This forms the insulating bush.

Similarly the battery negative cannot touch the pcb ground rail, as mentioned is at +4v wrt to batt -ve terminal.

S

[Aiko]

Hi guys! I am trying to make a concentric coil, but I do not know how should look the phase shift and the voltage of the pin 6 of the input amplifier. When I tune the coil what should I try to get - about a 200 mV amplitude (picture 1) or about 20 mV (picture 2). The blue line is the TX signal. Which one is better? What about the phase shift? Is it good on my scope shots?

[golfnut]

I think the amplitude you got is ok, sub 100mV is fine.


The phase delay is maybe a little high. I read on the IGSL / TGSL 20degrees is approaching a limit - if this holds for the idx your about 75deg.


This may not be as the design intended.


Do you have an IDX to try it on? You could test it and confirm or otherwise if 75deg is ok or not.

S

[verotopasera]

can someone please tell me what is value should be here
is there a precise scheme of this pcb

[ossamaussama]

Hello people! I adjusted the final circuit made by Eduardo, to make it fit on a 5x5 sheet of fiber, which is the standard that I get in my city. Here I share it, maybe someone needs it.

Regards

dose it work without vdi please

[ossamaussama]

Here it is and it works great. Is proved.

please dose it work without vdi?

[gtdavid]

hello,
where should i connect a scope to start testing on my board??
i am playing around with a sound card scope (i know , i know ) just for a look.
if i connect it up to tx it says that i have 15 khz !! i put a cap accross tx and managed to bring it down to 7 khz..
what other points should i test from??
thanks

[golfnut]

you could looka t the comparator input on disc CH and see a down-UP-down for non Fe targets and the inverse for Fe targets.

If you trigger on Tx, you can look at geb gating pulse and whatch it move about WRT to Tx as u adjust the geb control


Also dont trust the frequency count on these pc scopes unti you prove its not lying - see if the timebase is giving the correct time for one cycle and do 1/t for freq in Hz

S

[gtdavid]

sorry i do not understand the last bit my time go's from 0 - 1m and freq is 15.444khz