K7102 - Metal Detector

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1

i bought the K7102 - Metal Detector Kit from you, i tried it on the blue board but it dosent work!!
the LED must go out but in my circuit the LED is dimming but it dosent go out comletely!
so what do you thing the poblem is ??

and about the coile, what happen if the number if turnes is not exsately 120 and 43?!!

and i really need to understand the operation and how the circuit works?

Thanx

2

Check complete assembly.
Experiment with number of windings on largest coil.
Experiment with two supplied capacitors.
Sorry, no circuit descriptions.

3

for the capacitors, in the diagram, what value of capacitor should i use? for C1 ?

4

There are two caps supplied. Try both of them.

5

Good day!

I am also experiencing difficulties with Velleman K7102; e.g., it is not working.

I checked the assembly twice, also had my friend do it for me just in case. Tried with both caps, to no avail.
The circuit itself appears to be working, it goes trough calibration stage without difficulties and as intended. However, it doesnt react to metal in vicinity, in any way.

I checked the contacts, everything seems to work. The number of coil windings are correct +/- 5 for 120one, exact for smaller one. The direction is also ok, i checked it repeatedly.

Two things spring to mind:

  1. as i went trough coil winding, i had little room for all 120 winds, it looks a bit messy but no messier then on product pictures presented. A few winds may overlap, im not sure how much effect that can make. Any advice on that?
  2. during assembly i set up the speaker before first try; not an original one (cant buy it here), but one that has same specs. It works almost perfectly, if compared to LED.

I would appretiate any advice on the matter, as im not sure what to do next.

Thank you!

6

Overlapping windings is not a problem.
Hard to tell without actually being able to examine your assembly.
Can you post hi-res pics of both component and solderside ?

7

Thanks for your quick reply, will post pictures ASAP.

8

Ok, here are the pictures. Hope the quality is sufficient, its the best i could do in short time.



Never uploaded images here before, hope this works ok. Case it doesnt, im providing links below.
Anyway, hope this will help a bit. My only guess is that i did something wrong with coil. I did burn the tips (to remove the enamel), but its possible i did something wrong; still looking forward to second opinion!

Thanks for your time!

Ps. Pictures links, in case above doesnt work.
img222.imageshack.us/i/image032.jpg/
img51.imageshack.us/i/image029w.jpg/
img51.imageshack.us/i/image022d.jpg/

9

Looks OK.
Did you measure continuity of coil windings with a multimeter ?

10

Not yet, i borrowed my multimeter some time ago:(

I’ll try resoldering the coil, i can do that right now; hope i’ll get my meter this week.
If i have any luck, i’ll report my progress.

In the mean time, thanks again for checking out the pics, i was looking forward to a second opinion.

Cheers!

11

hi
im trying to solder this circuit , i hope it works but i need to add something to the circuit. what can i add?

12

Hi again, it’s been some time, still haven’t solved my problem:( At least got my multimeter back.

Anyway, here are the measured values across the board, i hope it will help somewhat. These are taken with LED barely working, as should be with calibrated circuit.

R2 (470) 6.71V
R1 (330) 0.07V
ZD 2.37V
R5 (10k) 0V
R4 (2k7) 1.78V
C1 (122) 0V
R3 (470) 0.01V
D1 0.59V
C2 2.37V
LED 1.79V

Ueb	Uce	Ucb /[V]

T1 1.79 0 1.79
T2 0 1.79 1.79
T3 -0.6 7.16 6.59

I can’t guess whether these are ok for this circuit; C1 shows 0V, R5 too, not sure if thats expected. Haven’t measured currents as that would take dismantling the circuit and i’m neglecting to do that until it proves to be necessary.
Any further advice would be most welcome.

Thank you again!

13

Sorry, these figures do not allow us to troubleshoot your unit.
We’d suggest that you return your assembly for inspection to:

Velleman Kit Tech. Dept.
Legen Heirweg 33
9890 Gavere
Belgium

14

I’m having trouble with the metal detector to work, bought the kit Velleman k7102 and I did a copper plate equal to the plate kit and does not work. And this all well mounted, which will be the problem?
Rui Mário - PT

15

Sorry, I’m sure you’ll understand that we cannot support copies of our kits.
Please use the supplied PCB to built and test the circuit.

16

Not exactly copies I bought the kit, but buy yourself oh yes he was right, but thanks the same but this already working, I had to take the varnish tips copper wire and soldered the ends to the pins. It’s what I had to do I loop a homemade card because it is for a project and have to be all done by me. thanks again

17

Not exactly copies I bought the kit, but buy yourself but had reason bought, but thanks the same but this already functioning. And I had to make a plate because it’s for a project.

18

Sorry that does not look like a Velleman project.

19

I have questions.
What I use is a beginner metal detector kit .
I am wondering this one is a great starter detector.

http://www.kingdetector.com/md3500-gold-finders-for-beginners-p-18.html