Prompted to get off my arse and do some work by a fellow detectorists progress on his Surf PI, Ive spent some time today getting the project a little further on.
The first task was to piece and drill the holes for the controls, and to create the hole pattern for the speaker. One of the controls (the sensitivity) has a bit too long a shaft but i'll decide whether or not to cut that down at a later date. The loudspeaker is not yet secured, there will be a layer of mylar film between it and the holes. The speaker holes are all 2mm, which will help against most splashes.
With the batteries installed and the coil connected above. Ive used twin shielded loudspeaker cable, which I just happen to have lots of.Only one core is used, giving a spare should the cable be damaged. This extra length of 'floating' copper doesnt seem to have any detrimental effect.
The test bed setup is shown below. In this configuration it 'see's' a small jubilee clip at about six inches, and a small pair of long nose pliers at around 8inch. Oddly it doesnt detect at all a two inch long phosphor bronze heatsink retaining clip! Must remember to try that against the Ace 250!
The final photo here shows the unit fully boxed . The next job, once the speaker is secured, will be to build a shaft and mountings. Once thats done, I can decide on a coil housing and a final coil.