Whites Surf PI schematic

[starmoml]

tanks

[daverave]

what components do i change so i can have a variable coil power control ????

[Tepco]

Variable coil power usually means varying pulse width, in this case varying R2 value, between pin 6 and 7 of 555. Increasing resistance will increase TX pulse width, and power consumption too, lowering it will produce shorter pulse, also frequency will be affected to some small degree. Exact timing can be calculated from 555 data sheet, or using numerous online calculators, like http://freespace.virgin.net/matt.wai...y/pinouts/555/ Better leave it as is, more effect can be achieved by varying minimal sampling delay, decreasing R25 value and adjusting R3 for minimal sampling time available for given coil. Suitable fast coil, and optimally adjusted dumping resistor R6 value is needed to best exploit this change, usually scope is necessary for optimal adjustment.

[daverave]

if i increase coil power will i get a few more inches of depth at the expense of battery consumption...or can i use a better first amp that is less noisy...if so what op amp you advise ????

[Tepco]

Right question is what you want to find , what object type, size and material, and under what condition (soil, water...). Surf cannot be made “better” than it already is, just can be tweaked and tailored to perform better under some particular set of conditions (but then underperform under some other conditions). More or less, matter of compromise, what you are willing to sacrifice, like battery consumption, or sensitivity to small, or large objects, and for what purpose, then modification can go in sometime radially different directions.

[starmoml]

High-frequency deep down low sensitivity to gold
Good sensitivity to high-frequency shallow gold

[daverave]

im not that interested in finding modern coins...i want to try and find small and larger gold items on the wet sand...so do i need high or low frequency and what should the detector parameters be for this type of searching.

[daverave]

i also see whites do a dual field coil....would that improve proformance instead of increasing power to coil...can this dual field coil be home made and if so are there any diagrams to show the wiring for this coil ???

[Davor]

Dual field coil is well described in White's patent. It consists of two coils, and each coil is dampened with its dedicated resistor. The field beneath it is more uniform, but as the non-uniformity obeys roughly the square law and targets respond at 6th power law, it is certainly an improvement but not by much.

[starmoml]

how much Self capacity?

[Davor]

What do you mean by self capacity?

[starmoml]

Coil capacity((mh)

[starmoml]

re

1: Schematic and the latest changes in the circuit in this photo?
2: The other site had been told: bc327 should be rotated 180 degrees, is this true?

[starmoml]

Capacity induction coil?
the pulse generator can be used instead of 555 ؟؟((toko))

[starmoml]

Does anyone has this circuit pcb؟؟؟
http://www.geotech1.com/forums/showt...hlight=surf+pi