Whites Surf PI schematic

[Tepco]

Looks reasonable, but one suggestion for bit more drawing: most resistors can be rearranged to 500mil raster, more natural and recommended, instead of 400mil, intended for 1\16W or smaller components, normal 1\4 or 1\8W size must be forced to fit, will try remake of this in Protel. Merely aesthetic rework.

[walkman]

my pcb.

Friends, Would you please check the error. Is this the latest updated version?

[Watanabe]

Thanks Tepco.

[daverave]

if i decided to alter the tx pulse width and frequency what would be the max you would advise...im not too bothered abut battery consumption...as long that i get good depth on gold rings on a wet salt beach...i want a detector that is also good at pinpointing and no ground effect from wet salt....if i increased the current from 37ma to 100ma and the frequency to 1500hz am i going to run into problems ?????

[mohandes]

how much voltage and Fercance TP ???????

hi my friend
please put for me surf pi pcbs here
thanks

[Tepco]

Hello Tepco .
What is the performance of your " Surfenstain " ?
How far to detect a currency ( 1 euro or equivalent ) .
Have some video of the operation ?


Thank you.

Just to add bit more confusion about SurfPI stuff, this is one, I acidenally stumbled upon it in old backup file. Built many years ago, bit modified surf, I lost schematic, never made video but PCB is 100% OK and tested, with just some minor modifications, can be interesting to someone. This incarnation may have 3 benefits, for different use.


1. Audio is separated from detector operating freq. and can be adjusted independently, also audio out is bit stronger, capable to drive low Z speaker or headphones, or both simultaniosly. Originally intended for small 32 Ohm buzzer, audio adjusted to it's natural resonant freq. around 2.5-3kHz, can be very loud, especially underwater, can be used without headphones or speaker. But later I find more interesting use for this:


2. This circuit is very suitable for timing modifications, this is about original, but if you want to modify it, say operate at 5kHs, short pulse, short sample, with some component value changes, fact that audio is independently adjustable is very useful. Operating at 5kHz, original synchronized audio is good just for mosquito repealing, not detecting.


3. PCB is made to fit into very professional looking but expensive BOPLA Alubos ABPH 800-150 enclosure. Just enough space for PCB, 9AA sized rechargeable batteries and controls. However, this is not good idea anymore. In good old days, many years ago, these enclosures were quality made in, presumably Germany, with very high quality silicone gaskets, nice surface finish and quality Al alloy. Making it very easy to waterproof, not for some serious underwater use, but enough for 1-2m. Last “good” enclosures I ordered from reihelt.de some 10 or more years ago. Recent boxes, obtained from another distributor are unfortunately different. Low quality ordinary rubber gasket instead of high quality silicone, poor surface finish, cheapest possible alloy probably made from recycled beer cans, this is hardly even rainproof, probably will fail even original IP65 certification. Only, still expensive.


What can be expected from modified detector depends on intended use. With suitable timing modification it can perform miracles in air test but actual use is limited. Short pulse, high repetition is always beneficial for smaller objects, fast sampling too, but... perfect for neutral soils, like sand and riverbanks or lake water, actually produced some very nice finds. Not for salt water, no benefit of very short delays, also not for mineralized soils, lacking GB ability. Actually, some very rudimentary form of GB can be added even to surf, but with significant performance loss, no advantage, not designed for that purpose really. For playing with timing modifications, better made HHd, it is flexible too (in VCO mode only), nicely documented, readily made PCB and kits are available, don't mess with this.


Few more remarks, no idea why input amp resistor is 2.2K on PCB, use 1K, use 5534, or any suitable chip, LM318 is faster but more noisy. Offset adjustment is generic, any op-amp can be used. DI\offset is for critical adjustment for very fast sampling, on the “edge” of waveform, preventing integrator saturation in early time, but chip other than 358 must be used (probably was TL272), or just omit it for normal coil. Delay pot is between PD1 and PD2, 50K, trsh. pot is 10K, no need for darlington in audio.

[maxm3s]

this were my findings

[maxm3s]

I finally got my work pi surfing thanks to everyone for the tips Geotech site, did field testing and this is the result

[kt315]

..

[kt315]

Mihai, if you want to learn more about the sensitivity of pi detector to gold you may find this into INSIDE THE METAL DETECTOR book. there are not secrets for anybody.

regards

[mihai001]

Hi
I am from Romania.
I want to make surf pi detector but they have no good deep range so please help which is best for gold ring and they have good deep rang (minimum 15 inch)
Thanks,

[daverave]

can anyone pls tell me how to adjust the offset control correctly on the 1st amp on the surf pi...with the delay set at max im getting nearly 12" on a 9ct wedding band ring...is that about correct for one of these detectors...also is the screen from the coil connected to ground or to the + of the battery cause i read the + is classed as ground on a pi detectors....my coil is 400 mH at 5 ohms and im not getting any ringing with the standard 390 ohm damping resistor...would i need to change this value ????

[WM6]

does the power supply could be cause of this ??

Of course it could be. Take batteries or accu as testing power supply.

[daverave]

is the audio output on the surf pi ok for driving pietzo headphones ????....on my tesoro lobo i can just about hear the audio with these headphones

ive solved the audio headphone problem and all is well now

[daverave]

is the audio output on the surf pi ok for driving pietzo headphones ????....on my tesoro lobo i can just about hear the audio with these headphones