This isn't really an area I covered in my Fisher Fury R1 kit car build as I kept it all very simple but, for this car I'm planning a much more advanced set of instrumentation, video recording, data logging and communications. By electronics I mean:
- Digital and analogue inputs required to perform vehicle data logging.
- Electronics to drive a display with some key information, described below.
- High definition front and rear 'safety' cameras built 'invisibly' into the bodywork, with automatic journey recording and collision/event capture (whilst moving and parked).
- Data logging for various analogue and digital sensors.
- GPS position, altitude and speed data.
- Digital 'sports' video capture and storage.
- Wireless communications for telemetry data.
The first question I'm currently trying to answer is ... 'Is it not just easier to use an off the shelf system?'
It would certainly be easier just to do it all on a high resolution OLED display so that you can choose and change the graphics at will. A decent large Smartphone or tablet screen would be up to the job.
The need to capture two HD video channels (possibly more) leads me to think I need bespoke hardware.
The data logger needs to capture all of the data available via the interfaces, described below.
Needs to be small and compact, quick boot time, low power, low weight, capable of being driven off a 12V power supply. A key requirement is that it can drive a 7" high-resolution display.
I'm going to need an I/O interface board with numerous analogue and digital inputs. This will interface to the data logger and display module.
There are currently 8 digital inputs planned:
- Data logging on/off
- Brake pedal
- Fan on/off
- Fan manual over-ride
- Mileometer (counter)
- Speed (pulse train)
- Tachometer (pulse train)
There are currently 11 analogue inputs planned:
- Accelerometers x-axis
- Accelerometers y-axis
- Accelerometers z-axis
- Air intake temperature
- Battery voltage
- Brake pressure
- Fuel level
- Oil pressure
- Oil temperature
- Throttle position
- Water temperature
- Current gear
- GPS (serial)
- Real-time clock
|A simple single-pole, single-throw (SPST) switch operates this main lighting relay [29.5g]. It has four pairs of contacts. One pair switches off power to the day-time driving lights. Another pair switches power on to the front side lights. Another pair switches power on to rear side lights. The final pair switches power to the high-off-low light switch mounted on the paddle shift. This then switches this power to the two high-power relays controlling the high beam and low beam headlights.|
Indicators / Turn Signals & Hazard Lights
Have spent some time thinking about it, I plan a very different approach to that taken in my Fury R1 with the indicators and hazards. Partly this is driven by the requirement to use LED lighting and partly by the requirements of the IVA, which requires the hazard lights and hazard warning light to work when the ignition is switched off. Mainly it is driven by the desire to save more weight and to use simple single pole switches.
The electronic flasher module in itself isn't much lighter than a commercial off-the-shelf module. The real weight savings come from much simpler wiring and the low currents involved mean I can use much thinner (and lighter) wiring. The hazard switch used is now also a simple, light SPST (single pole, single throw) latching switch to match the others too.
The design is split into two parts:
- Logic and timing board - connects to the indicator and light hazard switches.
- Output board - connects power to the lamps via relays.
I've used some diodes, a 555 timer and a logic IC (CMOS 4081 quad 2-input AND) to control power transistors, one for the left indicators and another for the right. This means there is a clear separation between the low current signalling and actual powering of the indicators lights. Legally, these have to flash at a rate between 60 and 120 times per minute.
Full circuit design and circuit board layout will appear here very soon. I've built it and it is currently being tested.
|This is the two-channel indicator output board [13.8g]. It uses two relays, driven by BC338 transistors. These are used to provide an audible click when the indicators are in use.|