IDX-PRO+VDI

[karim1189]

thank you

[karim1189]

hello guys, and I finally 'got the kit to build, but' I have not found any pattern inside. you have some scheme recently so I can check?
[ATTACH]28882[/ATTACH]

please gerber file of IDX

[Ruben2000]

To your scheme

Hi Aleks85, could you please share the SprintLayout PCB in .lay format?

[Aleks85]

No problem
https://disk.yandex.ru/d/zYsBjHcJGuF7ow

[gurdal]

Thank you very much Aleks85

[Ruben2000]

Thank you so much, Aleks85, for sharing with us all!
Have you built the IDX Pro using this PCB?
If so, what details should I keep in mind to successfully build it?

[Aleks85]

Yes, I built a Whites on this board. I used an AD548 input op amp, which is the best alternative to the LF441, and I used an LF444 instead of the LF347 – everything worked perfectly. It's hard to find high-quality ICs in my region, which is very important. It's also important to set the exact frequency – 6.59 kHz and 4.6 kHz. This metal detector is single-tone, so it's a good idea to use a VDI adapter on the PIC microcontroller, but the device works perfectly without it too. The main thing is to use high-quality electronic components, and everything will work perfectly.

[Ruben2000]

Thank you so much Aleks85 for the details!

[h9361]

Hello Dear All
I used this PCB and replaced BC517 in this point ( red circle) with revers its pins.
But this BC517 will be very hot as soon as turning on.
I checked all connections and lines, no problem.
Do you have any suggestion?

[gurdal]

Use 50-ohm speakers.
If the PP button is on, set the Threshold knob to the middle position.

[boilcoil]

As far as I can see from the circuit and the attached PCB, this is the final transistor for the speaker. Since the speaker is connected directly to the transistor (class A, without a separating capacitor), the current through it is equal to the current through the transistor.
As a first measure, see if you are not using a speaker with normal resistance (4, 8 Ohms) - the resistance of the speaker shown in the circuit must be greater than 50 Ohms.
If your speaker meets this condition, try to reduce the current through this transistor by opening the previous transistor more ( BC 237 according to the circuit). At first, try changing the resistors R55 and R54, and if there is no effect, you will have to tune the output level of U7a (LM393).
The purpose of all these manipulations is to increase the potential at the base of Q3 ( BC 237) to make it more conductive, which will reduce the current through the final transistor.


PS: gurdal wrote it before me.

[Aleks85]

I didn't have a 50 ohm speaker, so I used a speaker from a large pair of headphones, its impedance was 30 ohms - everything worked fine, the sound was loud, and I didn't make any changes to the circuit.
You need to carefully look at the BC517 pinout, it can be different, I use a transistor tester to check it GM328

[eduardo1979]

Hello Dear All
I used this PCB and replaced BC517 in this point ( red circle) with revers its pins.
But this BC517 will be very hot as soon as turning on.
I checked all connections and lines, no problem.
Do you have any suggestion?

The polarity of the transistor pins is very important. Some manufacturers change the pin order. I recommend using the MPSA13 or MPSA14. You also need to correctly configure the threshold level with the Pin-Point button pressed, ensuring the sound is soft and not bothersome. A very high threshold level can cause the transistor to overheat.

[h9361]

The polarity of the transistor pins is very important. Some manufacturers change the pin order. I recommend using the MPSA13 or MPSA14. You also need to correctly configure the threshold level with the Pin-Point button pressed, ensuring the sound is soft and not bothersome. A very high threshold level can cause the transistor to overheat.

Thanks eduardo1979.
I corrected transistor pins, it is not hot anymore but i have no audio in speaker, even with rotating threshold.
I checked 400Hs output with scope, i have this frequency from pin1-U7 (lm393).
I checked voltage of base bc547 (before MPSA13), it is 0.2V without connecting any coil.
I also checked base MPSA13, it is 3V !
Voltage of pin1- U6 (358 is 0.3V). I changed threshold, no change voltage in pin1-u6.

[eduardo1979]

That's very strange. This circuit works perfectly. Many people on the forum have built it and everything has worked flawlessly. You probably have a faulty component. Double-check everything.