I need help with idx pro silverdog red pcb!!

[eduardo1979]

Have you connected the 33nF and 1uF capacitors in parallel with the TX and RX coils?
Without those capacitors the detector will never work. In parallel with the TX coil, the 1uF capacitor is connected, and in parallel with the coil RX, the 33nF capacitor is connected.
It would be best if you put a picture of your coils, because the fault could be there.

[chiuino]

No eduardo my coils are umbalanced and for reach 6.5Khz i have mount 3 or 4 capacitors! but if you say this, i rewind a coils and perform measurement for exact mH and impedance....i have bought the exact size of wire that i read on forum 0.70 and 0.18 mm!!!
But if this is true why my detector at the beginning have ringed with some pieces of iron and with my cellphone?
Thx

This is the coil tx 0.5 and rx 0.35(too much big)

[lamoiz]

Hello,
I have the same circuit of silverdog.
I also had a problem, but my fault ... I replaced the lm358 by a 4558 ... and so it does not work. J had manufactured a concentric coil but the operation is not good. Made a double d in 27 ... but after measurement, the tx made 1.5R for 550mh son 0.25 ... this work @ 6.70khz ..... and not 6.59 with 1uf it goes to 6.67 khz. My question to the gurus of the site is: is it a problem if the frequency is a little higher?
Moreover, I find that sensitivity is not very good.
Thank you all for your help .

[lamoiz]

oupss.. 0.25 for rx coil ...
it s 0.8 for tx ..... sorry

[Wahyu]

Hi eduardo and Lamoiz

I have problem Q4 BC517, always getting Hot, with or without sound beep.

[lamoiz]

Hello, check r39 .. 22k, the meaning of Q3 is it good? It is the power supply of your circuit? L impedance of the hp? I am not a specialist..but this is the first test to do. good luck .

[Wahyu]

Thank for reply lamoiz,

i use 8ohm speaker, and i use lithum bateray 12v, what volt at R39 22K?

[CDI]

Hi eduardo and Lamoiz

I have problem Q4 BC517, always getting Hot, with or without sound beep.

BC517 has different pinout than mpsa13, check that transistor, also try to replace U4.

[Wahyu]

Hello CDI,

ok i will, i use this schematic


everything ok, discrimination work great, just BC517 getting hot
for U3 i use TL074 , and U4 LM393

thank for reply

[kt315]

check modulation signal from U7 Q3.

[gaby_sult]

Hello CDI,

ok i will, i use this schematic
[ATTACH]38933[/ATTACH]

everything ok, discrimination work great, just BC517 getting hot
for U3 i use TL074 , and U4 LM393

thank for reply

[CDI]

One stupid question: but, how much voltage u have on battery? I ask u this cause last time when i builded IDX for a friend, the same 517 audio transistor was hot after 5 minutes.
I had 4 lithium batteries 3.7v in series, which gives more than 20v when full charged.
Later when i removed one of those, everything was ok, bc517 remain cold.

[chiuino]

Some info before making the coils....
What is the right parameter in coil calcualtor for making 27DD coil?

In a discussion i had read this:

Actually, you can do a simple calculation:
D_Coil_Half_Circumference = (D_Coil_Diameter + PI * C_Coil_Diam / 2)
D_Coil_as_Circle_Diam = (D_Coil_Half_Circumf / PI)
Then just use D_Coil_as_Circ_Diam , in a Coil Calculator to get Inductance.

So, it seems that the D Coil Half as a Full Circle Diameter is about :
D_Coil_Half_as_Circ_Diam = (0.82 * D_Coil_Full_Diam)

So:
27cm DD Coil Diam => 22cm Diam as Full Circle <----someone confirm that this is correct?
13.5cm DD Diam => 11cm Diam
21cm DD Diam => 17cm Diam
41cm DD Diam => 33.5cm Diam
ecc. ecc.

All this because the data that is reported on the forum about 27DD coil with 0.7mm wire on calculator with 35 winding not correspond at 0.587 mH


Thx in advance!

[Wahyu]

Hi CDI, i use lipo bat 3cell , at full charge 12.6v, still hot without sound.
Hi my friend gaby, thank for pcb

[chiuino]

Sorry for insistence but i need info before making coils
Someone can delete my doubt with a answer?

What is the right parameter in coil calcualtor for making 27DD coil?

In a discussion i had read this:

Actually, you can do a simple calculation:
D_Coil_Half_Circumference = (D_Coil_Diameter + PI * C_Coil_Diam / 2)
D_Coil_as_Circle_Diam = (D_Coil_Half_Circumf / PI)
Then just use D_Coil_as_Circ_Diam , in a Coil Calculator to get Inductance.

So, it seems that the D Coil Half as a Full Circle Diameter is about :
D_Coil_Half_as_Circ_Diam = (0.82 * D_Coil_Full_Diam)

So:
27cm DD Coil Diam => 22cm Diam as Full Circle <----someone confirm that this is correct?
13.5cm DD Diam => 11cm Diam
21cm DD Diam => 17cm Diam
41cm DD Diam => 33.5cm Diam
ecc. ecc.

All this because the data that is reported on the forum about 27DD coil with 0.7mm wire on calculator with 35 winding not correspond at 0.587 mH
IMG_20170227_145953.jpg

Thx to all!