IDX-PRO+VDI

[dbanner]

Your coil maybe for Fisher 1265x. Tx...2.2mH/Rx...10.4mH
This is closer to your coil.

Maybe you do not have quick silver coil.

[dbanner]

Fisher Quicksilver coilRx 6.7mH/31ohmsTx 0.96mH/3.1ohms With the values for caps that Ivconic posted:Tx resonant frequency with 330nF......8.7kHz Rx resonant frequency with 33nF cap.....10.7kHz Which Fisher coil do you have? Your inductance measurements are different.

[Koala]

I don't think Fisher coil will work. The RX inductance is too low for this design.

Maybe you can remove the tuning cap altogether from the RX coil and leave it broadband. See what happens.

It appears the CZ 10.5" can be tuned to work

https://www.geotech1.com/forums/showthread.php?18051-IDX-PRO-VDI&p=141103#post141103

https://www.geotech1.com/forums/showthread.php?18051-IDX-PRO-VDI&p=133292#post133292

[gurdal]

pcb and connection

Try this circuit, it is taken from Cscope 1220b metal detector. Nice vco sound.

Look for the complete vco circuit (the audio amp is missing from the ltspice circuit) by searching for the 1220b schematic here on the forum. I'm will show you how to do he circuit is connected to the rest.

Hello friends,

i love this sound
can you draw pcb to test?
wiring diagram is important.
Best regards

[dbanner]

I don't think Fisher coil will work. The RX inductance is too low for this design.

Maybe you can remove the tuning cap altogether from the RX coil and leave it broadband. See what happens.

[tomec123]

Hi
Yes, it will be so. Have tested again this afternoon and indeed the disc does not work, the GB does not work exactly as already mentioned.
The original IDX coil (Bluemax 950) and its replica work without problems.
Now the question arises for me how to get there ... I didn't actually want to buy an oscilloscope ... but if there is no other way ... hmmm.
Where must the TX / RX signals for the oscilloscope then be tapped?

[dbanner]

I was under the he impression that the Fisher coil inductance was close to the idx coil requirements. Apparently this is not so.

The idx coil build document calls for a RX coil of 35mH, the Fisher coil is 11mH or thereabouts.

I don't think the phases will be correct and the disc and gb range would be off.

[dbanner]

Hello dbanner

I don't have an oscilloscope, but I'll try the tip with the 100k pot. Thanks for that. Where must this be soldered in?
TX out to RX in?

Tune the respective coils for the proper resonant frequencies, 6.59kHz and 4.68kHz.

Everything should fall into place.

I think the CZ coil is balanced for minimum residual voltage on the RX coil. So long as you put the correct value tuning caps, then it should be good.

Use this app for resonance calculations. It is superb.

https://m.apkpure.com/resonance-calculator/com.myg.android.apps.rc

If after tuning the coil you still cannot get proper gb range, then you need oscilloscope to see the phases, and know what's going on.

You can use a feedback arrangement for adjustment of phase and voltage, but an oscilloscope is absolutely required.

[Koala]

Hello Koala
I think there is not only one coil type for the Fisher CZ on the market, or it has been changed.
My coil has on RX 38,6ohm and 11,1mH and TX 4,9ohm and 2,5mH
this side: https://www.electronicdeveloper.de/L...lresinanz.aspx
give out this cabs: 104nF on the RX and 233nF at the TX side....

looks to be in the right ball park here Ivconic

10.5" Quciksilver

TX= 3.1 ohms and RX=30.5 ohms

probably just need to increase the Tx capacitor to fetch the ground balance inline.

[tomec123]

Hello Koala
I think there is not only one coil type for the Fisher CZ on the market, or it has been changed.
My coil has on RX 38,6ohm and 11,1mH and TX 4,9ohm and 2,5mH
this side: https://www.electronicdeveloper.de/L...lresinanz.aspx
give out this cabs: 104nF on the RX and 233nF at the TX side....

[tomec123]

Hello dbanner

I don't have an oscilloscope, but I'll try the tip with the 100k pot. Thanks for that. Where must this be soldered in?
TX out to RX in?

[liekwang]

TR7, TR8 and TR9, use any general purpose NPN transistor like 2N2222.

For TR10, TR11, try 2N2907 PNP transistor or similar

ok thanks for the information, is there any 2 audio input cscope audio input cd4013 pin 11 and input R62

[dbanner]

TR7, TR8 and TR9, use any general purpose NPN transistor like 2N2222.

For TR10, TR11, try 2N2907 PNP transistor or similar

[liekwang]

liekwang --- It is for PI

yes for pi but i haven't tried whether it can be used I highway it can be used for idx but who knows what the tone will be like

[liekwang]

Try this circuit, it is taken from Cscope 1220b metal detector. Nice vco sound.

Look for the complete vco circuit (the audio amp is missing from the ltspice circuit) by searching for the 1220b schematic here on the forum. I'm will show you how to do he circuit is connected to the rest.

dbanner is there in this one who knows what transistor is used in cscope1220B audio

https://www.geotech1.com/forums/showthread.php?14058-Cscope-1220B-Schematic&highlight=1220B