Tag: Design

More (Smart) LEDs

The Talisman V2 is using the CPU already included in the WiFi radio.  This Wifi CPU has less control wires made available than what was available from the independent CPU controller in Talisman V1.

In Talisman V1 there were 3 full color LEDs. Each full color LED used 3 wires – one wire for each of the red, green and blue LEDs. Therefore the Talisman V1 had used 9 control wires. (3 sets of 3 wires.)

Smart LEDs are being used in Talisman V2 to reduce the number of control wires. A large number of smart LED can all be controlled from one single control wire.

(This is achieved by sending the necessary color data for all the RGB LEDs over the single wire into the first LED. The first led then daisy chains the data passed along to the next LED in the sequence.)

The image above shows a V1 Talisman LED that with 3 wires on the left. On the right animated image is single smart LED. It can be seen in the right hand side photo that the little 5mm square LED has a dark chip rectangle and tiny gold wires within the white package. Each smart LED in V2 comes with a little chip inbuilt!

So, this posts shares how it is possible to reduce the number of data control wire by the use of smart LEDs from 9 to 1.  In addition it is possible to daisy chain a very large number of smart LEDs in a long sequence.

It is intended to add additional full color LEDs onto the Talisman V2, most likely in a circular ring or oval layout. This should allow the Talisman V2 to be orientated anyway an artists chooses. The Talisman V1 only had LEDs on the front edge, so V1 had to be orientated a certain way when artistically mounting.

Prototyping the smartLEDs today, uncovered a downside; they use power even when no light is being emitted! In fact their little internal chip uses so much power even when dark that they would over time significantly reduce the battery life.   For this reason it is necessary for the Talisman V2 to switch power off for the LEDs unless they are going to be shining.

It so happens that there is already a spare switched power available on the Talisman V2. The Talisman V1 used to have a Bluetooth controller that had it’s power turned on and off. This bluetooth is no longer required, so the second switched power is now used for powering on and off all the smart LEDs on V2.

Sugru and Conformal Coating Samples

The Talisman V2 is shifting the choice of the encapsulation or packaging of the internal electronics to other artistic people. it is suggested that one potential possible packaging could be the use of the end user mouldable Sugru.

A sample 3 pack of safe, family friendly Sugru has been ordered. The white color was choosen to allow the light from the colored LEDs on the electronics to shine through the hardened rubbery Sugru.

To ensure the waterproof seal and to avoid any shear stress ripping the electronics off the circuit board, a thin layer of clear soft rubbery “conformal coating” will be sprayed over the completed circuit board.

Coating the electronics in a paper thin layer of conformal coating will allow the encapsulated unit to receive thermal heating and cooling expansion and contraction movement, along with physical knock stress. The layer of rubbery conformal coating allows the components to squidge against the rubber layer.

Conformal coating is an expensive specialists coating, available in small quantities by 3M (via RS Components) as an aerosol spray dispenser can.

More power

In the Version 2 of the Talisman change to using a WiFi radio module has necessitated an increase in the capabilities of the power supply components.  The Wifi radio module requires more current be provided than was available in the original Talisman circuit. This has resulted in a simple upgrade of the voltage regulator to a different component that is capable of delivering bursts of more power.

AP2112K-3-3-112-AP2112-TRG1-3-3-V-0-6A-SOT25-20pcs-lot-Free-shipping.jpg_220x220

The selected voltage regulator, AP2112_3.3 is the same physical size as used on the original Talisman. Upgrading the power supply section of the electronic design will ensure that the upgraded radio module will be able to obtain stable WiFi connections.

Replaceable Battery

The design revision for Talisman V2 includes the ability to replace the rechargeable battery without the need to solder. The Talisman V2 uses a plug in connector between the battery and the main circuit board.

 

This will allow the installation of a replacement battery without the need to solder the two battery wires.  The actual ability to replace the battery will depend on the case encapsulation used and choosen by the various artists.

In theory it should be possible to cut and peel away any silicon rubber case from Sugru. The actual reality of being able to remove whatever case is used is questionable. However assuming the artist’s case can be removed, the use of a connector removes the earlier requirement for soldering the battery.

The images show the battery with the plug on the end of the battery wires, and the white socket that is soldered onto the main electronic circuit board.