Whites Surf PI schematic

[jap]

I think the problem is in the negative voltage (V-).
V- is equal at -2.8 V.
The correct value would be -5V??


Thank you.

Hi Watanabe
-To get -V=-5v ---> test & change u6,C13,C14,C15,,,[Make sure the polarity].
best time
j.

[Watanabe]

TP2 is at the output of the preamp, and the signal is seriously underdamped. If you have a 380R damping resistor fitted, then the problem is probably your coil. What is its inductance?

I used:
24 AWG
20 turns
23cm diameter
R= +- 1.9 ohm
Inductance i don't know...


Thanks


(still don't works......)

[Watanabe]

It may appear as a square even if everything else works well. The exponential drop of the signal may certainly look as square. So what do you do to obtain a square?

adjusting P1, TP2 is square:

T = 1,6ms; +V = 4V ; -V = 1,8V (characteristics of TP2).

Thanks.

[jap]

Hi Watanabe
-u Inductance is 282uH.
- IF u do not adj. -v=-5v it no work.that u can not adj. offset.
best time
j.

[Davor]

You could make a close up photo of your surf. There might be something that someone will see in it to correct your problem.

Turning the P1 to produce a square is not a solution. Check if anything is heating.

[Gorango]

Hi ppl,can someone help me? I can't find MC14093B nowhere. Is there anything else i could use?

[Gorango]

Hi ppl,can someone help me? I can't find MC14093B nowhere. Is there anything else i could use?

BTW i will use 18awg wire for my coil,is it too thick?

[Davor]

Seek CD4093

[Gorango]

Thank you very much Davor

[andva]

Hi All!

I've built the Surf Pi detector. Coil is 0.56mm enameled copper wire, diameter 10", 26 turns. Resistance is about 1.7 Ohms. The pulses are 34us long. The PCB is Surf XX design of ApBerg. Almost every function works fine, but I have two problems.

The first is: I'm not sure if the delay works properly. If I'm right, this function is theoretically for distinguish between the large and small objects. If I turn the delay potentiometer, there is no change in detection range of small or big targets (in air test). Where should I check it out by oscilloscope and how could I make the delay work?

The other thing is the false signals caused by wet grass or snow. The machine does not detect the ground, but wet grass often disturbs it. The coil is wound of enameled copper wire on a plywood form and is not shielded. The false signals also appear when I touch the coil with my hand (no sound when touched with plastic or wood). I guess the coil capacitance might be too high because of the too close windings. Did anyone experience the same problem? Should i make an other coil using pvc coated wire? May this coil affect delay function?

Thank you for your help!

[konan]

I have a problem, I made surf pi about year ago it work well bat sadnely treshold potentiometer has stop working. So now detector work with pore performancy, I change potrntiometer but stell dont work. I change lm358 and 4066, 4093 bat nothing chage... Any sugestion?

[Gorango]

I have a problem, I made surf pi about year ago it work well bat sadnely treshold potentiometer has stop working. So now detector work with pore performancy, I change potrntiometer but stell dont work. I change lm358 and 4066, 4093 bat nothing chage... Any sugestion?

Did you check your coil?

[konan]

Thanks I resolv problem.

I have another question for all, what values surf pi mast have on TP, I asume that surf must have this on TP2


What is with others TP ?

[Gorango]

Thanks I resolv problem.

It would be nice if you share with us how did you solv the problem,just in case if someone else have the same trouble.

[konan]

It was bad cabel from PCB to potentiometer...