Whites Surf PI schematic

[escarabajo]

I only have experienced with a coil, 9.5 "(23 cm approximately), 20 turns of magnet wire gauge AWG 24 (0.64 mm) and the maximum distance for a coin of 2.5 cm diameter is 28 cm. According to data in this forum, the sensitivity and depth of detection of 28 cm., it is acceptable for the surf pi.
Maybe you can turn the circuit more sensitive, by turning the sensitivity potentiometer completely to the right, but the circuit becomes unstable.

I do not use a radial coil, like the picture of Dimovnis, my coil is only 20 turns with a 9.5" diametes very tigth.

to get more depth in your circuit, you can tunnig the delay potentiometer slowly,and test the sensitivity, to reach the maximum.

[paku]

?Surf pi Board long print layout arberg I get sensitip in 9 cm gold rings and coins almunium. Size 2, 5 cm aerial just get sensitive distance 20 cm diameter 9 cm coil and wire 0, 5 mm 24lilitan what should be modified in order to reach a depth of 30 cm please me greetings from indonesia

24lilitan << 24 round

[liekwang]

?What Influences when the voltage the current Fed's surf pi 12 volts dc 3.5am

[liekwang]

?Surf pi Board long print layout arberg I get sensitip in 9 cm gold rings and coins almunium. Size 2, 5 cm aerial just get sensitive distance 20 cm diameter 9 cm coil and wire 0, 5 mm 24lilitan what should be modified in order to reach a depth of 30 cm please me greetings from indonesia

[inio_01]

Hello everyone


Thank you Jose that's what I needed


Regards

[Jose]

Hello
I have a question how it should look the signal at the collector of transistor Q1?,


Regards

Q1 collector waveform, approximately 17 volts.

[inio_01]

Hello
After assembling a long plate detector work properly about 30 seconds, then started to heat up the IRF, which consequently burned along with tlc 555, after investigation the cause was C2 (1000uF) which also heated up , replaced the burned items. I have a question how it should look the signal at the collector of transistor Q1?, on a base is the signal from the 3 pin NE555, the emitter v. 11.8


Regards

[liekwang]

Hi all I'm interested in the PCB Board ApBer with a long Board and simple do this Board work what is the path and its components in accordance with PCB layout Board I would like to try to make this Board does really work for anyone in this forum please give me explanation thank you

[Jose]

The first page starts by explaining that this design can be used with discrimination (for gold) using the Delay Pot.
Is this true ? - On a later page, discrimination was brushed off as not part of the design.

Discrimination as such, does not exist, what happens is that when the control delay increases, the detector is less sensitive to aluminum foil, less sensitive to some bottle caps depending on their composition, and gold, while still detected with good signal, bronze coins and iron.
This in a way is some discrimination, that in certain cases it may be useful.
You can increase the delay time as shown on the first page and then experiment with different materials to see what their effects.
José

[jlsilicon]

The first page starts by explaining that this design can be used with discrimination (for gold) using the Delay Pot.
Is this true ? - On a later page, discrimination was brushed off as not part of the design.

[Jose]

I had problems with the Surf PI, already discuss elsewhere in the forum, but I repeat again, to try and help those in trouble.
The cause was a malfunction of T1, apparently by the type of 555 that I'm using, producing poor bias of this transistor
This transistor (T1), saturated and collector pulses are weak or low amplitude making it run incorrectly the 4093, the pulse delay, appears immediately after the pulse TX, (no delay work), producing MD malfunction.
The best way to check if T1 works well, is with the oscilloscope.
Without oscilloscope, you can measure the voltage between collector T1 and GND, and should be around 3.8 volts.
If the voltage is higher, in my case was 11 volts, then T1 is not working properly.
I solved the failure by installing a 3.3K resistor between emitter and base of T1. Jose

[paku]

i make long pcb my problem is same like dimovnis

[escarabajo]

Hello Divmovis, when assembling my surf pi circuit, also had trouble adjusting, detected only a very short range.
After an oscilloscope and instructions I found on the forum so fit.
If you have no oscilloscope can do the following:
1. - Put a voltmeter between the center pin and turn delay potentiometer to read 4.80 volts.
Two. - Turn the potentiometer sensitivity or gain to a minimum.
Three. - Turn the potentiometer to the minimum threshold, you will hear a continuous tone.
4.-turn potentiometer sill slowly, until you hear a slight tone, almost audible and leave it.
5.-With potentiometer or gain to the minimum sensitivity tests for detection with different metals and slowly turn it to increase the range of detection.
6. - When you hear the tone becomes unstable, turns a little more threshold potentiometer, to achieve maximum detection range without the threshold to become unstable.


my coil is 23 turns of AWG24 magnet wire , a diameter of 9.5 inches, and 1.3 ohm.

the shape of my coil is not spiral like you coil, is only 23 turns with 9.5 inchs diameter tight with plastic ties.


damping resistor 330 ohm.


Best Regards.

Escarabajo

[Tepco]

This is really unbelievable failure, it reacts only to magnet. Seems that RX part is OK, 555 works, so check two possible issues. Most probably TX power pulse is missing (drive is OK), something around MOSFET, check soldering, PCB, transistor itself etc. Use multimeter to monitor current consumption, with and without coil connected, if it is about same, this is the problem. Also check your coil, just in case two parts made of two different wires may be connected in wrong direction (opposed, instead in series). Not to mention, you will need another coil.

[dimovnis]

My surf began to run, but poorly. Reacting only on audio speakers, a second metal is not recognized, iron, silver, gold, aluminum finish does not see ... This is my video please big help.