IDX-PRO+VDI

[6666]

Thanks Kilner
I had been fiddling with the C1 C2 buttons on the bottom of the view screen
when the program starts up
and nothing was changing but now I see when you press file, print
a whole new screen appears and from there you can select what you want to print
with C1 C2 etc, well I hope somebody else trying to figure this out will see this, I am embarrassed now
but glad I asked

[dfbowers]

Hi Don,

The series resistor is to fine adjust the RX phase. It also raises the Q of the coil. Nothing to do with nulling. Which is mechanical. White's did put a high mega ohm resistor between the TX and RX windings which I never understood. I guessed it was for static dissipation? Maybe nulling.

Make your windings matching the inductance then add a resistor in series with the RX to equal the original total of 111 ohms.

regards

I'm in the process of winding a pair of DD coils..

Can anyone comment on the general layout of the RX coil?

Thanks..
Don

[dfbowers]

I finished the IDX kit from Silverdog, minus the VDI module as I do not plan on using it.

Everything works fine, but I was looking for more. With the stock 9.5 coil from my XLT, I could only detect rings and coins to about 25cm. Then I realized that the offset on pins 1 & 14 of U3 was a mV or 2 below ground potential. The signal just has too far to go to trigger the inputs on U4!

I am using the LM324 from the supplied parts from silverdog instead of an LF347. In looking at the specs for the LF347 is can have an offset as high as 5mV!!. With no way to adjust the offset of quad op-amps, I just implemented the same fix as I used with the TGSL. It allows you to adjust the reference voltage slightly negative so the LM393 can trigger earlier. This brings the detection range to 40CM for coins and rings,, the ragged edge of the detection range for the stock 9.5 concentric coil.

This may be a band-aid fix and may be a symptom of another problem, but I'm not sure what. I just figured out a fix..

Don

Sure enough.. This was a "bandaid" approach. I replaced my LM324 with an LF347 and that cured my bad offset problem.

Don

[Wiltran]

Sure enough.. This was a "bandaid" approach. I replaced my LM324 with an LF347 and that cured my bad offset problem.

Don

Don, just to be sure I understand you, are you saying that the 324 should not be used?
Also I would like to do your tgsl sensitivity upgrade to my IDX, please could you post the schematic changes to the IDX and new connections thanks.

[dfbowers]

Don, just to be sure I understand you, are you saying that the 324 should not be used?
Also I would like to do your tgsl sensitivity upgrade to my IDX, please could you post the schematic changes to the IDX and new connections thanks.

The LM324 should work just fine. Actually, the LM324 seems to be less noisy than the LF347 but I have not tried a handful of them yet. I have only made my observation base on 2 ICs.

Just so happens that my LM324 had an output offset of - .010V !!! With the offset being so far negative, it had a long ways to go to trigger the LM393s, so sensitivity appeared to be not so good.

By adding the mod documented earlier in this thread, it allowed me to adjust the reference voltage slightly negative to get closer to the output levels of the LM324s. It's a great fix.. Same idea that I used with the TGSL.

The offset from the LF347 that I am using now is as close to 0V as I can measure. This makes the mod unnecessary. Just choose your ICs wisely and you should not have a problem.

Don

[golfnut]

The bottom one will be wideband (low Q) low R low output more BW

Top one will be narrow band (Hi Q)

[dfbowers]

IDX Quick connect diagram

Don

[Schatztaucher]

hey don,
great work .... I hope my idx works as good as yours, if it is ready.
Perhaps you could also connectors for the vdi mark on the circuit board? I've done it myself ... just to be sure ....

regards, marc

[dfbowers]

hey don,
great work .... I hope my idx works as good as yours, if it is ready.
Perhaps you could also connectors for the vdi mark on the circuit board? I've done it myself ... just to be sure ....

regards, marc

Marc,

I have the VDI Module on order from Silverdog, so I will update the diagram when I get mine running. I could in the meantime update it based on what others have documented earlier in the thread.

Thanks
Don

[simonbaker]

schematic

I hope to locate a schematic file for silverdog's pcb, hopefully in ExpressPCB schematic format. If someone can post a link to the most recent version I'd appreciate it.

-SB

[Schatztaucher]

would someone please check the connections from the vdi?

Would be super nice if someone would check the connections vdi ....

Many greetings marc

[holyuser]

Looks rightly.

[Schatztaucher]

many thanks!

[bernte_one]

yes yes everytime the same problems with the pots
good luck with vdi
dont forget to link your testvideo
will be my next too, at moment i solder two baracuda parallel

nice weekend, spring comes

[Schatztaucher]

Of course I'll make a clip .... I'm still waiting for the call from www.spulen.com that I can pick up my wire. the shop is directly in my neighborhood .... unfortunately the lady who winds up the wire just sick. I hope that it works next week. will also ask me what it costs, a coil winding can be. I read on the website, they also finished coils offer ....

regards, marc