Build

[Winnie the Poo]

Gosh. I appear to have worked out how to add images. Bit big, but they're there
So this is the finished build - Mk4 in the end, and I think the final take. It may look a sprawling mess, but that kit fits in the Ryanair cabin bag which can be worn over the shoulder, and I can take a walk in the mountains wearing the gloves. It has 2 battery packs - a 12v pack for the 4 channel power amp and a 2 socket 5v for the Raspberry Pi 3 and the HDMI Dolby 5.1 extractor

The (2nd hand) raspberry Pi plays a 2 hour 6 channel .ac3 file using Vimeo. It has a cheap touch screen fitted which I can't calibrate, so it is just a screen, and I use a wireless usb mouse to launch the music. The file is generated by code written by a friend, which produces a 4 channel WAV (which is enormous). That is imported into Audacity, where 2 blank channels are added, and the 4 active channels are assigned to FL FR RL RR. The file is then converted to ac3 using SOX.

Since the Pi outputs audio by HDMI - the Dolby 5.1 extractor was a compact sound card option. 4 RCA's link to the 4 channel 50W class D amp, which in turn feeds a box which adds a 47 ohm resistor in series to each channel to give more range on the pots, and protect the 3w exciters from accidental damage.

RJ45 sockets and leads are used for the connections. 8 way solderless, screwless modular junction blocks on a custom mount, make removal of the exciters for servicing and installation simpler. It also allows configurable lead arrangements. At the moment I have 2x1.5m ethernet cables, but I will get a 2m cable and have 1.5 m on the side nearest the bag, and 2m on the furthest from the bag

[Winnie the Poo]

The glove, made by my wife, is a Decathlon cycle glove with the fingers cut off, and an additional wrist band sewn to the wrist, which holds the solderless junction block . Cables to the exciters run through cloth sleeves attached to the fingerless glove, and these connect to a band which wraps round and holds the exciter box. This sleeve runs from the back of the box, over the box to the front, where it is attached by a popper, and to that is attached an elasticated strap with a velcro fastening

The exciters are held on the fingers by the adjustable elastic strap - to be secure, without squashing all the blood out of my fingers (pretty sure this is what the Tass gloves do too)

[Winnie the Poo]

This allows the box holding the audio exciter to be removed easily. The exciter is a tight fit in the box, and a bit fiddly and delicate for soldering the connections, so it needs to be removeable. The 8mm diameter screw head (again - same size as Tass) allows the height of the contact to be set - at 0.5mm. This is achieved , with the lid off the box, by using the edge of the lid as a "square" and adjusting the screw until the "square" just compresses the exciter suspension. It is then a "40 minute" anti-clockwise turn of the screw to set 0.5mm

It is possible to measure 0.05mm deflection from centre to peak , with a micrometer - which gives a 0.1mm peak to peak deflection (accurate to about +-0.01mm). That gives a volume control setting for about -18db from 1mm peak to peak. Assuming a linear pot about half way gives a further -6db to 0.0063 and half way again gives -6db to 0.003mm. Which is still detectable, especially if the housings are rested on my lap when worn. It may only be accurate to the nearest half-brick, but I think it brackets the range recommended by, and used by Peter Tass in his experiments.

I notice that the gloves seem to work best on the very quietest settings - which again fits with Peter Tass commentary.

[Winnie the Poo]

The exciter allows a slim finger profile, and provides an ample "piston" like action perpendicular to the skin. It's probably a bit more compliant than the EA C2 or Stanford custom LRA's and so probably needs to be run a "bit louder" - but it provides the correct localised, squashing vibration, in an entirely stable position on the finger, once properly adjusted

[Winnie the Poo]

A 3d printed box and lid hold the exciter fixed on the fingertip securely whilst providing some isolation for the rest of the finger. The 3d printed lid is shaped to hold the finger in place, and facilitate the 0.5mm skin indentation at rest. A 3d printed washer with a centre thread, and 3d printed screw, allow an adjustable precise contact point. Being plastic, they are unaffected by the magnet of the exciter (a problem with the previous steel versions). The washer is stuck to the exciter surface which is self adhesive

[Winnie the Poo]

Except I appear to have built this thread upside down. "Oh bother" said Winnie the Poo
Admin - can you mend it?