the PW Sandbanks

[C.Pruysers]

I was trying to get the Autotransformer as mentioned in the schematic ( TOKO ) . Nowhere to be found ! I built this PI detector my way , and it worked like a charm the first time . No difficult adjustments . Forget about the transformer . All the thing is doing is giving you an additional + 12V . I left out C4 , R8 , IC3 , C5 , R9 , R10 , Tr3 , the 87BX135 Transformer and D1 . I used a second set of batteries to get the +12v . So +12V direct to IC8 (in) . The - 12V goes to OV . The othe battery is hooked up as in the drawing . For Tr 4 you can use N Channel J FET 2N5459 ( bottom view GSD ) For the Tr6 you can use P Channel J FET 2N5461 ( bottom view GDS ) . You will see it works right away . Looking at the finished product I would say , if you never used a soldering gun do not start this project . Have fun . I am starting now to work on the Twin Loop Treasure Seeker . Just a lot of fun . Cornelius

[C.Pruysers]

Re: the PW Sandbanks

forgot to mention that you build all the parts on the print . Only the transformer is taken off . That way if you lateron want to try the transformer you still can do it when you feel like it . You do not put IC3 in . The minus side of D1 is soldered on the board . The Plus side is your connection for the additional +12V of the battery . As batteries I used two packs of 10 1.5 V batteries ( because of IC8 you have to have more than 12V to get a stable 12V ) . The batteries are not built into the detector case. I use a seperate battery pack on my belt . Easier to recharge them that way too .I made the audio changes ( R25 , C14 and the two capacitors of 10 nF ) . The Sandbanks works to all my expectations and is easily set to its highest sensitivity . As a case I used ( I like to build everything myself ) PVC airduct as found in the kitchen department of your hardware store . Size is 106 mm X 53 mm outside measured . The Sandbanks is only about 50 mm wide so you see with a little elbow grease you can make a nice case for it . Have fun . Up to the next one ! Cornelius

[Esteban Cabrera Grinok]

Re: the PW Sandbanks

If it has intention to construct the Twin Loop Seeker, both replaces transistors of power by Darlington TIP 112 or TIP 122. Use alkaline batteries.

[C.Pruysers]

Re: the PW Sandbanks

Thanks Esteban . I will give it a try . Kees

[C.Pruysers]

Re: the PW Sandbanks

Esteban . I tried the TIP 122 but had better result with the TIP 31C . That is how I will keep it for the time being . I will go now to the EE Treasure Hunter , and after that I will try to make a more powerful 2 Box Detector . Still working in the meantime on the Koehler principle of the Proton Mag . The actual Mag is too simply constructed while the border signal registration is too much for a field instrument . Just my opinion though . Kees