Saturday 27 July 2013

Fuse box - adding circuits - found the part numbers

I decided to take the dash off once more to:
  1. remove/replace the wiper motor cir-clip which I weakened when switching the park position (twice :)
  2. Add a couple of circuits for my speedo project and engine immobiliser
For the second of these I really wanted to add the circuits into the existing GBS Loom fusebox rather than inline fuses. There are plenty of spare sockets with live feeds from the bus bar, they just need fuses and the right sort of spade socket on the other side of the fuse to take the live line.

This is my fusebox - mounted upside down vs. normal builds due to my slightly different wiring route under my heater. In the fuse area you can see plenty of spare slots many already with 12v feeds on the right hand side of each fuse socket:


Its stumped me for months finding the right part (even consulting GBS didn't turn up a clue)  - but just as I was deciding to jury rig a normal spade connector I chanced upon a picture of the box on someones unrelated forum from a circa 2010 entry, he had a screen shot of the catalogue page...

The GBS stock fusebox is a Delphi part a 'modular fusebox' on/around page 7.2 of the Catalogue

I need to double check but it looks like:

   Fusebox is part #12191544 on page 7.8

   Fuse cover is part #15324032 on page 7.8 

   Pins are part  #12160636 on page 7.4 15mm centreline



Result!

Update - Ordered from Mouser (I couldn't find the part anywhere else), + a locking bar and fuse cover, just to mitigate their high shipping costs.

Update - Order arrived, I can confirm the above part numbers are correct.

Thursday 18 July 2013

Bonnet vents

Miles on the clock

My round trip to work is 84 miles, so over the last couple of weeks taking in the Zero now and again plus some spins out with colleagues at lunchtime has helped push the total milage past 1000 miles.

Good testing - need to keep an eye on the limited milage insurance though...

Everything has been fine, even in the summer heat & stop start of the M25; engine seems happy and the cooling system is just about able to hold the temperature when in standing traffic. The one big notice though is the engine heat has nowhere to go except finding holes in the pedal box into the footwells and down through the transmission tunnel to slowly cook the driver.

Vents

I'm fitting some bonnet vents to try and give the hot air an escape route and hopefully make things a little more comfortable when driving. I mocked up some options:



Eventually deciding on the last option: two or three small discrete vents on the trailing edge to also have mesh behind when I find the right product.

The sheet metal punch ordered and arrived from Ebay, it winds up with an allen key & punches through the stainless as if it was paper. First up a test on the bonnet cutout to check/confirm which way produces   a clean cut & that I'll end up with a half decent job. 20mm punched holes joined to make the slots:

Then on to marking up the offside. The slots are 20mm high with 10mm spacing. 
Drilling pattern is 4mm pilot holes, widened to 10mm then followed by the punch itself:


Holes all set:

Joined the dots with the Dremel cutting disc & then tidied & de-burred  with one of the Dremel stone wheels & sanding drum. Looks pretty much as expected, this has just been wiped with WD40 to take off the masking tape glue - it will get a proper clean when back on the car:


Both sides done & bonnet back on - all set pending some grille arriving to sit behind the holes. They're not right at the top so won't directly let the hottest air out but might setup a flow under the bonnet from the radiator and at least start moving air through:
















Update - I've been out a couple of times in similar heat - nothing definitive, the holes make a some difference - nothing dramatic - good job they look good! I think the next step will be wrapping the exhaust under the bonnet and/or even a vent in the top of the nose just behind the radiator.

Friday 12 July 2013

Debugging the digital speedo

Its Sunny !

The British summer turned up and the weather has been good for driving, so while there are over 800 miles on the clock now I've made no progress on the roof. 

Reminds me of an old cartoon in my favourite childhood book: Story Book Dictionary -now- Best Picture Dictionary Ever  by Richard Scarry

One of the Busy Town animals has a large hole in his roof:


Wow - just thought - theres my '80/20' rule or 'Good enough' lifestyle choice right there - learnt probably before I was 5 years old ha!


Digital Speedo Circuit Design

The circuit itself is cribbed from a number of forums existing projects etc & I found some great online tools for checking & drawing circuits:
  Circuit Lab allows full simulation over time & 30 day free trial
  Digikey Scheme It allows diagramming for free\

My current circuit intention is something like this:

S1,S2 - Front panel momentary select & reset buttons
R1,R2 - 5k6 pull-ups for the I2C bus
R3,R4 - 10k pull-downs on the switch inputs
R5,R6 - 200R current limiting on the 12v sensor inputs
D1,D2 - 5.1V voltage limiting Zener Diodes on the 12v sensor inputs

Mocked up currently looking like this:


+5v will be via a solid state regulator to drop me down from the car's 12v line

Inputs are 12v current and voltage protected with resistors & Zener diodes.

The illumination input will be to turn the brightness down rather than up - i.e. when instrument illumination is on its dark outside so I want to avoid glare from the LED display; not yet even mocked up.

The display is from ByVac and accepts an I2C/Serial input so I don't need a rats nest of wires/pull-ups to multiplex the 4x digits or continuously refresh it. In theory I2C bus can support multiple devices on its two wires so I could upgrade to a small LCD, Multiline or any I2C output device.

How long does debugging take...

Its been a while since I coded anything, its pretty good fun though;

I think I read somewhere (I could have the numbers completely wrong) you can write about 4 lines of bug free code a day - not through slow typing, just because debugging takes time. Arduino tools are pretty basic too, the debug cycle is to embed print statements in the code, download, run, monitor the serial output - no single stepping :/


Some progress though - the project has expanded & I now have basic menu code working for functions with two input buttons: select & reset. The functionality will be:
  • Speed - to 10ths of MPH
  • Selectable speed warnings at 30, 50 & 70 mph
  • Trip 1 & 2 - to 100ths & 10ths of a mile respectively
  • 0-60 timer - starts when the car starts moving or red button pushed
  • 1/4 mile timer - starts when the car starts moving or red button pushed
  • Calibration - on the fly tweak speed up/down & entry of pulses per mile - could even drive this via the USB/Serial input i.e. console base calibration.
  • Sense instrument illumination to adjust brightness

I'm trying to tidy up the timing code for measuring speed based on the time between bolts passing the speedo sensor but its been hit & miss without a proper function generator to test it. I have this rudimentary pulse generating code creating an output on one pin which I feed back into the sensor pin - hence that flying wire on the picture above taking the output back to the sensor input.

Unfortunately - up to a point - I am a perfectionist with code, keep tinkering, re-arranging, checking until it both works and looks pretty.


Update - the digital speedo is on hold until the dash next comes off and I add circuits - which wont be while the weather is so good!