One of the next jobs on my list is to look at the rest of the interior. I have managed to get hold of some original switchpacks for the air conditioning / fan and headlight controls - these go either side of the steering wheel and the LED intelligence will be handled by the new dash pod I've designed. Next up then are the two switchpacks either side of the stereo head-unit. To use the late model T-Car interior design, there is a fibreglass pod that holds the radio and houses these two non-symmetrical, rather nice looking switch packs that house controls for the window up / down function, door open and on the left pack only, door locks.
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| TVR T-Car Interior (Tamora, T350 & Sagaris Models) |
Fairly early in my plan, I decided that I really wanted to integrate heated seats into the car. On cooler days it's really nice to run with the roof off, but it can get a bit chilly so heated seats will be a welcome addition! Looking at the aftermarket kits however, they all seem to come with horrible aftermarket car switchgear, which just won't work, so I wanted to integrate the controls in so they look like they came from the factory. To do that I have an extra button on the left - the door lock button that I don't consider I will ever need; I had such a button in my old Chimaera for nearly 15 years and I don't think I've ever used it! This is only one button though, I need 2 to control both sides.
My initial plan was to try and make a copy of the left hand plate and copy it over to the right; this would give me a button and an LED previously used for alarm function (I hate those so intended not to use it). Fairly quickly I found that sourcing any of these original switchpacks though was nigh on impossible - just as well I was planning to make my own! This meant that I'd need to make two in any eventuality. A bit of luck struck and I managed to find a pair of original aluminium plates from new old stock - these had no buttons or circuitry, so wouldn't be much use to build, but they did give me a great opportunity to trace the original shape to be able to replicate them.
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| Original TVR Switchpack pictures (from a forum member) |
After a few attempts, I found that placing the unit onto a high quality photocopier at work with a blue plastic background gave the best results in terms of a clear, 100% scale image that I could trace in Autodesk Inventor and reproduce the outline shape.
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| Original TVR Aluminium Plate - Front Scan |
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| Original TVR Aluminium Plate - Rear Scan |
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| Tracing the Scanned Image in Autodesk Inventor |
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| Resulting Solid |
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| Print Test to Check Scaling - Fits Perfectly! |
With that exercise complete, I now had a good digital base from which to start. I was a little worried that simply mirroring the unit was going to create a problem with the overall width. Using a mirror of the left plate on the right hand side added around 2cm to the overall assembly, which was going to push the pod very close to the neighboring air vent which I decided was going to look a bit weird.
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| Original TVR Design with modified LEDs (much smaller and now two of them) with mirrored design |
Since I had to make just about everything from scratch though, I could technically do anything I wanted with the design with the only issue being some potential fibreglassing to fit the altered shape, which *should* be fairly easy to do prior to trimming the interior. With that in mind, I created a new design using the same TVR design language of multi radius curves and circles to look futuristic but organic. Something I learned here is that multi-radius curves look a lot more natural than simple curves and is how a lot of the TVR design language works - it makes sense I suppose...
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| My new condensed design to bring the overall width a bit narrower |
Now to decide which I liked better! I want to make this car look OEM with a twist, but to make people double take when the see it, so going away from the TVR design is a little risky and if I'm going to do it then I want it to look like a model TVR could have released in full production rather than some weird prototype. I started by building up both designs with every component properly modeled. This also helped me understand how they work - each button has an acrylic light pipe ring around it, recessed slightly which I guess must be glued or press fit into the aluminium plate. The button then sits directly on top of an alps momentary switch and locates with a small cross in the back. The circuit board behind is held by some studs and standoffs so that the button spring holds the button in place (which has a small top-hat to prevent it falling out).
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| Mockup with a single DIN head unit dummy |
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| New design with a dummy Single DIN head unit dummy |
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I set about making all of the bits, then printing off some paper samples to offer up to a kind T350 owner's interior.
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| Original Mirrored Design |
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| New Design |
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| Clearance to air vent with Original mirrored design (without the additional trim around it) |
This kind of helped, but I was still in two minds about both designs, so after some head scratching, I rendered both designs and stacked them on top of a picture of a T-Car Interior. These sealed it - the new ones it is! They actually look really good I think once you can properly picture them in situ!
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| Original T-Car Design |
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| Overlay of Mirrored Original Design |
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| Overlay of New Design |
A fairly crude approach but it gives the best idea of what they'll look like I think! Fingers crossed that the real ones look good. I think should be able to fit fairly smoothly with a little fibreglass re-work of the pod and dash structure.
Next up then was to work out what the electronic side was going to look like so it was time to fire up Autodesk Eagle - my previous experience with the instrument pod made this a lot easier second time around, though I still needed to make a couple of custom libraries for components that I couldn't find in any of the usual spots online. I found that you can create libraries and import your own .stp 3d models of hardware which is a bit of a fiddly process, but this enables you to export a much more complete board step file with the components already fitted which in this case was very useful to see if my buttons and LEDs would line up with their corresponding holes when aligned to the studs fitted to the back of the aluminium plate.
A very simple circuit to create, but did take some work to get everything to line up perfectly and have correct clearances for nuts and studs and things like that. For the button backlights, the light pipes each have a pair of LEDs in a recessed space in the ally plate. I left an output from the dash instrument pod so I can control these on a PWM circuit so I can control brightness and make some neat effects like fade on and off, maybe a slow pulsating glow effect if the ignition is on but the car not running - plenty of scope for coolness. I guess one question is on colour - for now I've selected blue LEDs to match the numbers on the instrument pod (and colour of the car).
One other small point actually was the
Seat Heat Kit. The kit comes with a couple of momentary push buttons to activate the heaters, and the little brain box includes over-current protection, timers to switch off or prevent overheating and things like that - I want to keep all of this function and importantly the LED indicators. To spec my board though I needed to know what if any resistors to put in line with my indicator LEDs to prevent under or over current. Thankfully I managed to find some nice pictures online of someone who already attempted this which gives me some confidence that the brain box already includes resistance so I have not included it on my board (worst case I can add it in the wiring external to these swichpacks).
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| Back of Seat Heater Buttons (this one is a dual switch plate version) |
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| "Brain Box" from the seat heating kit showing resistors bottom right of the board |
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| Eagle Schematic (LH Plate) |
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| Board Design (LH Plate) |
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| PCB Design (Straight out of Autodesk Eagle with studs and spacers added) |
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| Buttons & light pipes added |
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| Front Plate added |
With the assembly designed and the packs looking pretty good, my next step is to get the PCBs built so I've drawn up the bill of materials (quite a short one!) for both boards, generated the gerber manufacturing files, and sent them off for quotation. All being well these will take around 1 month to produce. In the meantime I've been in contact with a friend with a CNC machine to look at the hardware design and make sure that the components are manufacturable. After some small tweaks to optimise the tooling required I think I have something that will work nicely, but I'll hold off on this phase until the PCBs are made to ensure the two will fit together by building one around the other, so with that - on to the next job!
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