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This is Progress?

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Medical Console PCB DesignWe’re a little further on in the design process now, so I thought I’d just blog about the progress (?) I’ve made with the electronics for the Medical Console kit. Firstly though, I thought I’d explain just why it’s come about that this electronics kit will have two printed circuit boards (pcbs) rather than just one.

The necessity for two boards was brought about by determining that the best location for the USB input and output ports was on the back wall of the main console section. Now, inside the main console was where I planned that the main board would be, so it very soon became apparent that the best solution was to have the USB ports mounted on a separate board to the main board, but for it to be a plug-in board mounted at right angles to the main board. It’s a tight fit in there!

Talking of the USB ports, assuming the modeller has chosen to light the model, (and if not, why not?!), the model will be powered via one of the (micro) USB ports from a standard mobile phone charger wall unit. If the modeller has also built the Wild House Models Stasis Pod kit then they can connect the two models together via the second USB port. The Stasis Pod will then be powered via the Medical Console and no matter which of the models functions are triggered by the ubiquitous key card, the actions of each of the two models will reflect the actions of the other. Both models are still capable of independent operation if desired however.

There is another, for us, novel feature of this new design. It is a bit of a departure from the philosophy of the previous, Stasis Pod, electronics design in that it is a bespoke board, designed in house, rather than being based on a commercially available board as was the Stasis Pod electronics kit. The new board is a ‘ground-up’ bespoke design but is still Atmel powered, in that I have used a (surface mounted) ATTiny 44 microprocessor which has ample power to perform the functions asked of it without being overkill. The PCB will also have the advantage of a simple plug in programming facility should the occasion arise.

Anyway, moving on, the other day our postman delivered to me a rather intriguing package. Inside were a whole load of polystyrene peanuts and hidden amongst them were the first 3D Printed Parts of the three screen frames and the side Pod indicator panel, as well as three printed transparent screens. I can now carry out some “real world” trials to test the installation of the screen illumination LEDs and the magnetic switching sensor.

Sample LED Lighting Test on the screen

My first lighting trial, using a small bench vice, sticky tape, black insulation tape and a bench power supply seems to have had an unexpected result. The LED is positioned on the right hand side in the photo and you can see that light travels through the screen quite well, hence the bright area on the left hand side. We just have to work on getting the light more evenly distributed across the screen. I’ll try again when I’ve had chance to carry out some light blocking. You have to bear in mind though, these experiments are being tried out on the 3D Printed “bucks”, not the finished resin cast model parts, so light spill now is mainly because of the white translucent material of the 3D Parts. However, the screen printing is looking good!

Indicator panelPutting aside the screens, I turned to the indicator panel. After examining the indicator panel and relating it to the drawings of the rest of the side console, one thing did become very clear to me. There wouldn’t be room for my original idea of a separate pcb for the indicator LEDs to be mounted under it. Hmmmm, ok, let’s see you get out of this one, was my first thought!

Phew, I think I may have dodged the bullet on this one! After consulting with the team over this small setback, the answer looks like proving to be using fibre optic (FO) strands. To that end, I’ve re-tweaked the design of the main circuit board, and instead of providing four 5v tappings on the board for any DIY lighting, I’ve reduced it to two tappings and now plan to mount different colour leds on the board which will have fibre optic strands attached to them and fed through to the side pod indicator console where they can be inserted through the drilled out indicator light holes, in any order the modeler chooses. This method also has the advantage in that it gets around the other tricky problem of trying to feed electrical cables with connectors on through holes that are just too small!

Indicator Panel shelf part

Well, that was all the theory worked out, all I had to do was to apply the tweaks, or modifications, to the board design and all would be good. Ermmm – that was the plan anyway, but it didn’t work out quite as simply as that! Re-doing the electronic schematic was simple enough, but it wasn’t until I’d defined the board shape that I realized it was actually very slightly offset to one side. I had factored that in (smug mode on)….on the wrong side (smug mode off and collapse of stout party)!!! Gaaaaah – do it again you fool! So I did, twice! Eventually I’ve managed to produce a board profile that should be a nice snug fit inside the main console unit. As I mentioned earlier, I’ve worked closely with Roger, the CAD Engineer, to ensure that the main kit parts, when assembled, will retain the electronics without the need for any additional screws or spacers.

OK that just about covers all the planning, in my next set of ramblings, I’ll cover the practicalities of converting all that thinking into actual doing and reveal what the circuit will actually do! ‘Til then, keep tuned.

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