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Dipped sidelights


Paul Booth
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Getting itchy fingers waiting for odo to arrive and Japanese-Honda-manager to get back from wherever he's been holidaying, so...

 

between getting our refuse truck 205 DT ready to offload and replaced with a lightweight Ali trailer, I got to thinking about this whole side-lights/indicator lights bit.

 

Can anyone think of a reason why dim dipped headlights should fail at MOT time when used dimmed as side lights and normal brightness when switched to dipped headlights?

 

If not, I have a solution for converting the side lights into indicators and making the dipped headlights double as side lights in a dimmed operating mode. It just takes a couple of air cooled resistors, courtesy of Maplin.

 

Then I can chuck the stock indicators into the spares box.

 

BTW, while collecting a new 205 facelift indicator from a new & used bits centre in Gloucester, I noticed a family of repeaters, same size as the Supra's, and in every colour; red, purple, blue, green, white and even orange.

I was picturing a pair of red repeaters on the side of my red Supe. Hmmm!

 

 

(Edited by Paul Booth at 7:50 pm on Aug. 27, 2001)

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Spent some time reviewing the circuit against "The Good Book" (sad, I know) and worked out a much better solution: 'the fog lights'.

 

It's possible with 2 x 10W resistors, and little else (existing diodes in the side light circuit and the fog relay combine to provide isolation in each mode), to make the fog lights work as 5W side lights, when the side lights are on and the fog lights are 'off'.

Then to switch to full brightness when the fog lights are switched 'on'.

I assume there are no issues with there being no seperate side lights at that time.

 

It is then possible to wire the indicator circuit to the original sidelights and replace the bulbs with the appropriate alternative. The big orange lumps can the be discarded.

 

Any legal or logical flaws I'm missing here?

 

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I'm not sure about the nitty-gritty surrounding Construction & Use regulations.

 

What I would do is have a "flick a hidden switch" option that would put it all back to stock come MOT time. Though if you've designed something that was dedicated to junking the stock indicators entirely, i.e. fitting a new front section. Then that may not be a viable option.

 

I'd re-consider the big wirewound and use a Zener/R combination feeding the base of a power Darlington or something, as I think you will need an element of voltage stability.

 

Also, there is a nagging doubt in my mind about feeding the bulb with a reduced supply. It may well be that the bulb only gives out, say, 5W of light at a particular reduced voltage. But what about the colour temperature of the light?

 

I rather suspect that you may have to drive the bulb with a PWM supply. But then the question might be: Could you get the brightness reduced to the determined level without stroboscopic effects coming into play?

 

Yours,

J

 

 

 

 

 

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My thoughts went as follows:

 

There's no legal requirement for front facing fog lights, so if I was to replace the fog bulbs with 5W and make them the sides, this would be perfectly MOT'able.

 

I gave some thought to a Zener/Darlington arrangemenbt but then  I thought "there's no voltage regulation on the rest of the lighting circuit so why add any?".

In fact, over the required voltage range, a 6R8 resistor would have to dissipate between 9.6W(ish) and 13W(ish). So I ordered Ali cased HS50 units from RS. These will dissipate 50W heat sunk and 25W in free air.

 

With regard to the light output levels from a filament dissipating 5W electrically, but that is designed to operate at 45W electrically, you got me there. This is where I go to suck-it-and see mode. I think PWM is way over the top as I'd like this to be a mod anyone can do at reasonable cost (£4 so far).

 

Actually, my biggest concern is getting the all glass bulbs which fit the original sidelight mount sockets in 21W (which I will then have to paint orange). I have someone researching this for me.

 

 

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Darren,

 

The orifice is designed for a capless bulb and it's my assumption that the bulb glass needs to be kept as far away from the plastic lense inner as possible (stop it melting, basically).

 

So it looks like there are now 2 options 'cos I came up with another (never say die).

 

1.   By using a capsule Tungsten Halogen lamp with a 2 pin G4 base (it's quite small and pretty damned bright) and a porcelain G4 holder soldered into the original mounting, we have a fairly small but very bright unit. Yes, it would need painting orange, which is the big downside.

 

2.    I'm also gonna have a look at bastardising a standard bayonet base out of an old indicator mounting and see if: (a) I could get a standard bulb (as you described) into the hole and (b) if I could mate the bayonet base onto the original side light mounting.

 

I know I can do (1) but it then means painting the bulbs, plus they are a specialist supply (Maplin or RS are easiest)

 

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Paul, I still think you will have problems with colour temperature.

 

Also, I don't want you to think I'm simply pouring cold water on your ideas, a halogen bulb may not like being switched on and off quite so quick (Halogen cycle and all that).

 

Plus, it might not like being painted too. There's the heat question (though if it were flashing then okay it might not get so hot). But then there is the fact that *because* it wouldn't get so hot, the life of the filament could be drastically reduced.

 

It *is* a good idea, though, as it gets rid of the tatty indicators that look like they were sourced from a caravan & trailer store. Plus, when I make my new front, I can design in a couple of recesses for some nice eyeball-style foglamps.  

 

Yours,

J

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I have to say I was rapidly getting the point where it was becoming too complex, i.e., it has to be obvious and easy to do for me to publish the method and then completely wash my hands of it; which was the goal.

 

I too was concerned about the bulbs, for other reasons though. The only ones which would do the job are not designed with vibration in mind.

 

Oh and hey, I get really bored if there's no one playing Devil's Advocate. Way better to test ideas for flaws before you try it out, hence my posting *before* I started. It was just *so* cheap to try it, I thought it worth a play (also gets me out of the evil one's way - it's that special woman's time). Total money burned = £2 and change (assumiong I can  find a use for the other 6R8 25W resistors, if not I've burned about £6).

 

I'm determined to get rid of those truck side marker lamps in the air intakes so I'm considering other methods.

 

I'm now going to look for flush mounted side lights which could be mounted in the bumper and used as indicators, *not* the combination side/indicator units I have seen used; just simple white lens flush mounted units.

 

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Also, not sure if you are aware of this, you can now get a 21W bayonet-cap bulb that is designed to light up indicator orange, however, when it is switched off the glass is a silvery colour. So when it's fitted behind a white lens,  you dont get that awful fried-egg effect.

 

Might be just the ticket if you find some clear indicators to fit flush to the bumber.

 

Yours,

J  

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Don't laugh, but,

Landrover lenses screw into a base fitment. This could be mounted inside the bumper to give a flush fit. Liekwise you could do the same in the rear for fog lights. Advantages are the bulbs can be easily replaced because the lens screws off, they'll closely match the size of the rear lights.

 

As I said, don't laugh.

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Well, the thought of Paul driving around with Landrover lights did raise a chuckle I have to say. :)

 

But yes... sometimes the daftest-sounding ideas can throw up the most viable of solutions.

 

Yours,

J

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Quote: from Paul Booth on 3:32 pm on Aug. 28, 2001[br]

B*££*cks!

 

The all glass bulbs only come in 3W and 5W. If I can't mod the side light bulb holder easily to accept a standard bayonet fitting, it's a nice idea down the pan.

 

 

they're available in 16w .............. which is plenty bright enough

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Quote: from matt on 6:00 pm on Aug. 31, 2001[br]
Quote: from Paul Booth on 3:32 pm on Aug. 28, 2001[br]

B*££*cks!

 

The all glass bulbs only come in 3W and 5W. If I can't mod the side light bulb holder easily to accept a standard bayonet fitting, it's a nice idea down the pan.

 

 

they're available in 16w .............. which is plenty bright enough

 

16W *capless* bulbs??????

 

If you're 100%, seen it yourself, sure I *really* gotta stick the barbed wire stick up the rear end of the person looking at that for me, that would be the same one who got me a warning light panel when I

asked for the new Odo.

 

 

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