Power Testing

The components for the power management were added and tested successfully.

The reverse protection allows the user to apply charging power to the two screws in the wrong orientation without any damage.

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The battery charger IC charges the onboard Li-Po battery when power is applied to the two nuts. The charge current was measured at 45mA which could be reduced very easily by using a smaller configuration resistor.

The voltage regulator was tested and ensures a consistent 3.3 volt is supplied to the circuitry.

Silicon Mold – 2nd attempt

A second attempt was made to pour a silicon mold around the shaped resin form.

The pour was not the best, and the liquid resin did not flow correctly. An ugly bumpy lump of silicon can be seen in one corner. Normally the silicon would flow and form a very flat level on each half of the mold.

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The first attempt failed when attempting to degas the liquid silicon. In the first attempt the liquid silicon immediately cast inside the vacuum chamber into a spongy foam. The silicon resin was 12 months old, and has a recommended shelf life of 6 months.

It remains to see if this 2 part mold will be able to retain the resin without leaking!

 

Wireless Bridge – USB Module Parts

The parts to be used in the dongle that plugs into a computer arrived. The particular USB Module chosen was selected to work out of the box without requiring hunting for USB drivers.

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This module will be in a small enclosure along with a wireless Bluetooth module.

Together the USB module and the Bluetooth Module will allow a program running on a computer to bridge from the server, over the internet, through the USB module, into the Bluetooth module, over the RF airwaves, into the Talisman Bluetooth Module and finally onto the Talisman device.

Casting using Mold

A casting was prepared using the silicon mold. The casting was solid resin without any internal electronics. The purpose of the casting was to check if the silicon mold would seal correctly and not spill all the resin.   Surprisingly the very irregular silicon mold did not leak!

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The Top side shows a nice consistent ability to graduate the speckled texture to the top surface of the talisman. This texture is visible along with a smooth surface finish without bubbles. The talisman is cast upside down so the texture sinks to what will be the top surface. This is useful because the texture material has sunk and does not occlude the glow above the internal LED.

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Also any bubbles rise in the inverted mold and therefore problem bubbles appear on the underside of the Talisman. The top side of the talisman is at the bottom of the silicon mold and never has bubbles sinking down there.

 

The silicon mold was not perfect and a very clear parting line is visible around the talisman. Any blemishes and inperfections will be manually sanded down.

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Hopefully a better casting of the silicon mold would result in a less visible casting line. The silicon used in this mold was past it’s expiry date by 6 months and did not flow as well as fresh silicon.

The quantity of white pigment added to this test was hastily added at the last minute and not measured correctly. The resulting intensity of the whiteness is lower that required and this test therefore looks a lot more milky rather than a quartz like white that has been achieved previously.

 

PCB Arrived

The Printed Circuit Boards for the prototypes of the Talisman version 1 arrived. The quality of the manufacture looks good and there are no obvious errors.

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The next step is to populate the components onto the board and then begin the firmware programming.

It also looks like the resin master form and silicon mold that was prepared using a DIY printed PCB was the wrong size and scaled down a bit!

This means that it will be necessary to redo the casting and shaping of a master form using the received PCB. The received PCB are the correct size, and one will be used to create a cast of resin to be sculptured again.

 

 

 

150W Soldering Iron

The Talisman is secured with bolts that screw into M3 nuts that are on the top side of the PCB. The nuts are large and require additional heat to fully solder prior to the reflow soldering process.

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This large 150W soldering iron will enable manual soldering of the nuts on the top of the PCB prior to all other parts being placed and solder oven reflowed.