Rear Fog Switch

[WizardKing]

After doing the rear fog-light mod (i.e. uses bulbs in boot-lid as fogs or brake lights) I had to do something about the naff switch.

My original, beige, interior had the usual hole drilled next to the switch pod. When I changed to the black plastics, no hole . . . hooray !

I took the blank 'switch' out, chopped, changed and glued it to a mains switch, here's the result ;

32996

32997

[Turbo_Steve]

Does the switch light up / do you have an illuminating tell anywhere (e.g. in the dash).....think that's an MOT requirement?

Other than that - Lovely!

[Atik]

Yep, I believe it is an MOT requirement for there to be an indication that the fogs are on. Usually the button lights up, or a light on the dash.

My suggestion would be to wire up the existing dash spot with a bulb and run a feed to/from the switch ;) And in case the eagle eyed amongst you thinks that there isnt a rear fog icon on the dash, there is! It just hasnt been used. See this thread http://www.clubvr4.com/forum/showthread.php?t=39076&highlight=fog+light

[ANTHONY]

think that's an MOT requirement?
yep it is

[WizardKing]

Nope !
Cheers for the confirmation, I did wonder about the requirement.

Expect an update . . . soon.

[WizardKing]

Done ;

32999

[bluemooney]

nice
i got a mitsi one from a mitsi dealer 22 quid all in justgot to fit it

gaz

[WizardKing]

That's just cheating !

Good luck wiring it up, if anything like the front fog . . . [too many wires.]

[HOODY]

I was suprised how many wires came off the back of the fog light switch!

[WizardKing]

It reminds me of an attempt to baffle us with science [and force us into the nearest dealership !] Just like the computer world, really.
On a monitor's 15 pin plug, there are at least 7 common earths !

[Turbo_Steve]

It is actually done for a reason, as is the computer monitor.

[WizardKing]

Both ends are commoned, what possible reason can there be ?

Splitting an already common earth (both ends) is about as useful as the fact that over half the monitors I've seen use an inline choke/filter incorrectly, with the wire simply passing through it. [If it doesn't do a figure 8, it does nothing.]

[Turbo_Steve]

They're commoned, but they don't have to be.

Don't forget that the HD15 connector you see on a VGA plugs is actually a bastardisation of the full on 5 x BNC connections (R, G, B, H, V) which are traditionally completely seperate circuits, not least to allow an external sync generator to be used if you're vision mixing (stops the whole picture "revolving" every time you change sources). The monitor and the card both common these earths in an HD15, as they have to assume the other device won't. The joys of cross compatibility.

There are two more reasons:
1) Current. Your earth should always have the same current carrying capacity as your send. So you either have a big earth, or one for each send.

2) It's not just an earth. It should be listed as "earth\screen" on the schematic. Each 'signal' wire is individually wrapped in it's own earth in an effort to reduce cross talk and prevent RFI from being picked up.

If you've ever had to run a 15metre, 20metre of even 100metre VGA run, you have a choice: you either get clever and use special (expensive) line drivers to send it over twisted pairs. This uses ALL the cores in a Cat5 cable to traverse the 100m, and there ARE timing issues, even if you manually set the clocks at either end (there's our external clock again!) and you also still get voltage issues, with some colours oversaturating. And, of course, the more devices in the chain the more reflections, and timing issues you are likely to induce.

A pro-grade 100m VGA cable is massively thick, and mainly full of screening, and works best with each signal driven seperately.

The real pro stuff tends to be 5 seperate co-ax runs bundled, on proper BNC connectors with 75Ohm (iirc) termination at either end to reduce reflections.

I really need to get out more :(

Most of this has been replaced these days with software, which is great.....but still can have timing issues if not properly implemented, so you end up having sync-clocks on everything. Even then, video can still be problematic in multi-screen installations.

[Atik]

I was just about to say that, Steve beat me to it :D

[WizardKing]

" . . . of the full on 5 x BNC connections "

Still only adds up to ten wires, though (maximum.)

[Turbo_Steve]

There are only 5 earths in the VGA standard spec, dude.
There are four additional signal cables that are sometimes connected to earth: these should be 4 data lines (DCC, ID, something, and something else that I can't remember either). Two or Four of these are used as a serial communication protocol to identify the monitor type and allow more advanced power control states than simply disabling the horizonal sync and allowing the monitor to go into standby.

That's how windows knows what kind of monitor you have installed, and what capabilities it has. This is ONLY available on HD15, as the pro-level kit (with the 5 x BNCs) is supposedly only used by people who know what they're doing in terms of Vertical and Horizontal Sync Rate, overscan etc etc

[Turbo_Steve]

Ah...here we go...I wasn't QUITE right about the VESA implementation, but close enough:

http://pinouts.ru/Video/VGA15_pinout.shtml

[WizardKing]

Very informative answer, cheers Steve :scholar:




p.s.
As you're a rep whore . . .have one on me !

[Turbo_Steve]

A rep whore and a pedant and a fricken nerd. [/facepalm]

Thanks dude.