It started as an experiment with the LM3914 and ended up as a functioning, if rather makeshift, AFR meter:

• Made on breadboard - check
• Badly soldered - check
• Using mostly recycled components picked up off the floor - check
• Works perfectly - check
• Likely to earn me a disapproving chuckle from TSD - check

With a little more finesse it might look OK stuffed into the gauge cluster, I'm tempted to do another two for temperature and voltage, just need to work out how to work with the non-linear temperature sender (my electronics design is way too rusty for a simple thing like that).

For those who are interested, it gives a dot readout from 0-1v, as you can see there's very few components to it, the circuit is basically straight off the LM3914 datasheet with a tweaked reference resistor pair.

That looks pretty good, I scrounged a lamda sensor some years ago to make one but never got round to it..

Groovy.

Nothing wrong with veroboard, well it's a step up from poking components through cardboard and soldering wires on the back

I bet that last LED feels left out without it's own track

Now theres an idea. Didn't decide to go for the solid bar flash lighty when maxed out version thats on the data sheet then.

Didn't think it was really relevant to the AFR as it's very hard to be dangerously rich. It could perhaps be made to flash when really lean but TBH it was midnight and I couldn't be arsed

PCBs are not very hard to make, I made one;-)
I alterered a rev counter, the circuit board was pretty easy to make and suprisingly the rev counter worked...

Soooo..... it looks cool

electronics?
IN A LAND ROVER!!!!

lol its gonna be my specialty - oh dear

Do you do a TDi version?

It's entirely possible, yes.

Fridge - can you put the leds on an arc to match the circumferential curve at their radius? (In other words so they look like they fit! - God what a stupid way of writing it!).

Would look uber cool.

Al.

Al - I could, yes.

I could also buy more chips and cascade them to give higher resolution using smaller LED's.

Who knows what will happen depending how much time I have between now & Russia.

Oh dear.

Land Rovers.
Electronics.

Still, you can't do any worse than the factory efforts!

Cool - I still have that indicator stalk jobber for you, if its for Eddy.

Al.

What about going the other way and using a mod on the fuel gauge to read the sensor? Would fit, look right and not be quite so bling for us oldies

AndyG

Could do, but my new speedo has a fuel gauge on it:

very nice!

How does the speedo pickup work?

It's got a cable adapter, you can use a magnet and reed switch or a VR or hall pickup, or a speed transducer from an LT230, or...

Use the GPS signal, which then also controlls traction control?

i thought traction control was the throttle

For my rev counter I used an old abs sensor[99p on ebay] they are pretty easy to mount and fairly robust.

GPS wouldn't be fast enough for traction control - not a problem though as MS already has anti-rev traction control, I've just not worked out if it'd ever be useful. The LR ETC system is actually very effective but it would need extra hardware, and having lockers I can't see a need to fiddle.

Who, me? Nah, I dont get to dissaprove of that... I put one in a standard 52mm (?) guage housing about 6 years ago, before I'd even installed my first megasquirt. I'm not bling enough to use vero though, real engineers cut the tracks directly into plain board with a scalpel

It might still be around here someplace... will have a look.

It can be made to work if your GPS signal is good enough.
Retard the ignition very quick to reduce power and thats how that works.

how does that work Daan?

There are TC routines in development for MS (besides the existing rate-of-rise anti-rev one) although you could bodge it by connecting wheel speed sensors to a comparator and when a threshold is reached it triggers the knock sensor input on the MS, that would then do the retarding thing.

I guess the GPS setup would need to compare wheel speed to GPS speed to decide if you were spinning?

Would GPS have the resolution to do this?

Al.

it gets speed down pretty well Al

Most GPS receivers have an update frame time of 1s - that'd be pretty poor. the ETC i'm designing has a frame time of 4ms.

GPS is good for speed because it measures displacement over time, using a moving average i would imagine.

Unless of course you can get hold of GPS receivers with a quicker frame time? maybe DGPS/survey units can do it?

But even then, your speed is a derivative of your position (change of) - so is fundamentally limited by the resolution of the position no matter how fast you can sample. Thats whats confusing me.

But hey - if it works, it works!

Al.

Its been used in WRC for quite some time actually. The ecu compares wheelspeed with gps speed (in forward direction) and cuts engine power by retarding the ignition if it thinks there is too much power. If the GPS signal is not clear than a groundspeedsensor is used as the second option. this is basically a radar that looks forward down to the road at an angle. The radar sensor is now banned, but I think the GPS sensor could still be utilised for this.
Pi research did all the work for mainly Ford and Skoda.

Daan

wow, i woulda thought that the gps lag would have been an issue aswell, cos the problem is latency in the circuit (ie how instantaneous corrections are) and that this can be a problem just building normal traction control computers, let alone adding in a huge 2 way lag of talking to a satellite.

1 way. GPS receivers don't talk to satellites.

I don't know any details of the system Daan's talking about, but i think it's fair to say it'll be well removed from civilian/hobby GPS receivers.

well then, i apologise for my ignorance, i shall go and edumacate myself on gps

I know nothing about electronics but for the traction control with GPS I would have thought the system would just assume the speed had remained constant from the last GPS calculation which others have said may be a relatively large gap. During this time a faster calculation could be taking place using the wheel speed sensors and appropriate power reductions taking place.

Steve