External ambient temperature.

Hi All ,
One thing I think I’ll miss come the winter is an external outside air temperature reading or indicator.
Being someone with definite geek tendencies rather than go and buy an off the shelf widget, which would be boring I rigged this up:









Using the Arduino processor board and three LED’s to indicate cold(green), normal(yellow), and hot(red) with changeover temperatures of 20 and 25 Celsius; green below 20, yellow between 20 and 25, and red above 25.
The final incarnation will be just one RGB LED mounted somewhere that it’ll give a coloured glow of probably one of 6 colours - deep blue for anything below 5 C, maybe light blue for 5 to 10C, light green for 10 to 15, green for 15 to 20, orange for 20 to 25, and red for 25 and above. Just waiting on delivery of the RGB LED’s.
I suppose I could add a buzzer or some audio warning below 5 C although I think commercial manufacturers use 3/4 C.
Anyways now I’ve admitted to having too much time on my hands, I’ll bid to a good day.
Regards,
Michael

My MGF has the factory low temperature/ black ice warning system, something quite unusual on Oz market cars, down here in the south east of the country we do get black ice on rural roads.

This sort of stuff is right up my street. In retrospect I should have used an Arduino or a Ras' Pi at the heart of my electronic mods' but I was already committed to discreet units which monitor & inform. To rip it all out & start afresh would be a waste of time, besides some of the bits are quite inventive & I like them. It doesn't matter how clever your hardware & associate programming is you still have to get those signals out to do work in the real world, which means electronic switching & there's some great bits out there in e-bay land or the old standby, relays.
M

Hi,
Black ice in Oz? That does surprise me.

IMHO Rasps are far too bulky and OTT for this ( and other) added car features. The final version will be on an Arduino Micro or Nano, I’ve only got the UNO’s. Might have to use relays for a 12 V supply to the LED’s as some(the yellow one) are rubbish at the voltage pushed out. Unfortunately, that’ll mean I can’t use the PWM outputs so no colour mixing…..I’ll see how the RGB LEDs behave when they arrive.
Interesting how I went and bought a car that’s relatively simple from the onboard ‘tronics point of view and start adding ‘tronics! At least I know where they are and how to rip ‘em out if they start with a bad attitude.
Cheers,
Michael.

Yeah we get black ice in Victoria, Tasmania, the southern highlands of NSW and the ACT, not often but it does happen

Yes your right the Pi has been superseded, I use it as a catch all for one board micro’s. If I were to adopt a centralised control for all the junk I’ve included I’d use the Nano, (more Cambridge than Milan). However you have to get the “thinking” bit to do work, whether that is interpreting the change in current flow through a thermistor to operate LEDs or to interpret signals from other sensors around the car.
I love the idea of a single LED slowly transitioning from blue through to red but I’m not going to think too deeply, as that’s going to muscle in on what I’ve got & what is already in the pipeline.
The capacity of these “one boards” is remarkable & the price per project is next to nothing. I vividly recall the BBC model B & the facilities offered to the inventive but they were in a different price league.
I don’t know how many of you order bits for projects & by the time they land the design has changed or moved in a completely different direction.
My experimentation budget per project must be less than a fiver & if there’s progress I’ll spend a bit more.
I have a box in which I keep bits that have been superseded & “discarded”, quite frequently these have provided the springboard for other ideas.
Great keep us posted I’d love to see the end result.
M

The latest prototype. The RGB LED’s off EBay are a bit meh on non primary colours. Using relays and a proper 12V supply ensures good colours and brightness. Not exactly space saving though. Even more OTT!! Decisions, decisions.

With your earlier comment on adding “‘tronics” to a car with few trinkets, I happily identify with that sentiment. However even my megalomaniacal outlook couldn’t conceive a system as extensive as this to let you know that it’s cold / temperate / hot. A Jodrell Bank to two bean cans & string.
But I think it’s a brilliant project although I might have used three thermistors into window comparators driving your tricolour LED. I know that it’s an old way of approaching it & not really in the spirit of the thing but I’ve an old fashioned approach & I don’t touch spirits. I eagerly look forward to the next iteration.
M

Yes, this incarnation is ridiculously OTT. However, it got me thinking again of the ‘features’ added to current cars such as auto lights and wipers not to mention my favourite lane ‘assist’.

Rant: If you’re incapable of directing a vehicle within boundaries either side of it then perhaps you shouldn’t be anywhere near the vehicle let alone in charge of it.
End Rant. :slapme:

Anyhow, now to order an Arduino Nano and a suitable enclosure and get it fitted sans relays.
Regards,
Michael.

Lane assist was the first facility to be disabled when a new car, so equipped, lands on the drive!
I hated it from the moment I first experienced it.
Have you tried power mosfet switching, I’m sure you must have. I ended up with a box of tf style relays & used them extensively until I returned to some solid state switching I did several years ago. I’m slowly moving through various devices made with relays & replacing them.
I commented in an earlier post that I had a number of devices on the car which could be micro board controlled, one is auto lights & the other auto wipers.
M

Oops, apologies there Airportable. I’d obviously forgotten your reference to auto lights/wipers.
Actually, I’ve never tried MOSFET switching, mainly because I’ve never found relays problematic in their switching duties - the frequency mainly, but now you mention it….
Away to France tomorrow for a week so nothing will progress till after.
Cheers,
Michael.

It was a fast switching problem which forced me to try mosfets again, I then found another couple of applications where I wanted to switch a lot of amps but I couldn’t accommodate a fat enough relay in the space. The board I use have two fets & I simply parallel two boards if I need to increase the capacity.
Have a good trip & we will reconvene on your return.
M