Headlamp Modifications

Post by **mat_fenwick** » Thu May 27, 2010 5:06 pm

Bugger. Although I suspect it will still be Okish, as the easiest current path to earth is via the dipped beam filament of the second bulb. The path to earth via both main beam filaments will have almost twice the resistance (assuming 55/60w bulbs) so will see less current. Have to work out resistances to see whether it's an issue. Hmmm.

Don't spend too much time on it, but if we do work something out then I will definitely have to put it in after all this!

electrokid · Post by **electrokid** » Thu May 27, 2010 10:37 pm

Bugger.

Hahahaha - I had a feeling your next reply would start with something like that

I have to admit defeat myself at this stage - I have a circuit that should work but with 6 relays...

And I've spent most of the evening trying to find out how to use Ipswitch with my new (well 2 years ago anyway) webhost so my brain is a bit fried. I'm finding it hard to get my brain serviced now the local Woolworths has closed

... so here's my first attempt at posting a picture...

electrokid · Post by **electrokid** » Thu May 27, 2010 10:53 pm

PHEW !

Looks as though that works ! !

I'll do some more work on it tomorrow.

My natural inclination of course is to use power FETs and all sorts of clever electronicy stuff - but standard relays etc can be bought anywhere if there's a problem and it's far from home.

I learned this lesson the hard way - 1967 I was on the Isle of Man complete with my 1950 Morris Minor - the sticky-out indicators had been replaced with electronic flashing ones designed and built by yours truly - a fuel can in the boot wore away the insulation on a carelessly place wire in the boot - shorted out - and blew an OC35 transistor. No more indicators and no OC35s on the IoM that I could find.

Bulbs are funny things - their resistance is in milliohms until they get hot - any cct (including some of mine before I twigged) that has the 2 main beam filaments still connected will have a bright light one side and a very dim one the other.

I notice that the BX has a little control box by the OS headlamp - might be worth digging into.

Post by **mat_fenwick** » Thu May 27, 2010 11:43 pm

Thanks. What I'll probably do tomorrow is print it out a couple of times, and use a red pen to show the current paths in the different situations. I'll build the circuit off the car first, then I can just put the whole assembly in as a unit once I know it works.

Relays also have the advantage that I understand them completely, and can hear them operating. I'm still not sure I fully trust those new fangled transistor things!

Mike E (uk) · Post by **Mike E (uk)** » Fri May 28, 2010 12:24 am

2 bulbs inseries gives 1/4 the normal power in each bulb, which is probably similar to dim dip intensity.

But I am puzzled why you are bothering to try and keep the dim-dip at all.

I have never missed having it,after I removed it- and modern cars don't appear to have it anyway.

The wiring without it is so much simpler, plus I would not want to run bulbs in series because when one fails open circuit, both bulbs go out.

The simplicity thing wins for me though,my circuit uses 2 relays. If it goes wring I can fix it without much effort.

Plus the easier it is to fit, the more likely you are to fit it !

Mike

electrokid · Post by **electrokid** » Fri May 28, 2010 12:33 am

Circuit description...

Sidelamps on their own feed a normally connected (NC) relay contact which goes nowhere.

Iginition on its own operates RL3 but RL2 does not operate because of no volts from 'side'.

Side + ignition operates RL3 and RL2* and puts power from + (battery) to LH dip filament. Common of the LH bulb goes through the NC contact of RL4 to the RH dip filament.

Side + ignition + dip operates RL3, RL2* as above but also operates RL4 through a diode which grounds the common of the LH bulb and operates RL5* which provides + to the dip filament of the RH bulb.

** RL2 and RL5 are grounded through diodes through the main filaments of both bulbs. Only one diode is necessary - 2 are fitted - if one of the main filaments fails the circuit will still be operational.

Side + ignition + main operates RL1 and RL6 and maintains RL4 through a diode and because the main filaments now have 12v on them RL2 now turns OFF removing drive to the dip filaments. It also ensure that if dip happens to still be 'called' RL5 also cannot operate.

Clear as mud

Post by **mat_fenwick** » Fri May 28, 2010 12:34 am

Paranoia?
I tend to drive with my lights on a lot of the time (force of habit from motorcycling). This I tend to do using dim-dip rather than full strength dipped beam, as I often think that dipped beam seen when the car is going over bumps could be mis-interpreted as me flashing my lights to let someone out.
I like the efficiency in not using a resistor to drop the voltage, although I haven't actually worked out how much power is wasted in heat. I think I need more people to say it can't/shouldn't/won't be done - that will spur be on just to be stubborn!

electrokid · Post by **electrokid** » Fri May 28, 2010 12:39 am

DOH ! !

Side + dip without ignition only switches on one headlamp - there should be a diode between the top of RL2 and the top of RL5 - pointy end towards RL2.

Post by **mat_fenwick** » Fri May 28, 2010 12:56 am

Thanks for the explanation, I will look at it with a fresher brain tomorrow!

I'll get it once I trace the path.

KevR · Post by **KevR** » Fri May 28, 2010 9:39 am

Electrokid - you still haven't said why you need LHD headlamps! I'm curious!
I'm with Mike E on the simplicity angle. I might get round to fitting a couple of relays at some point - just done it on my BMW bike to improve the lights (using BX relays, naturally), and it makes a big difference. But I've got no complaints about the BX's lights anyway, despite the fact I use yellow halogen bulbs rather than fancy Xenon white ones. The car's not fast enough to need lots of light!
Also, not even sure if I've got a dim/dip facility. Certainly never knowingly used it.

electrokid · Post by **electrokid** » Fri May 28, 2010 11:14 am

Electrokid - you still haven't said why you need LHD headlamps! I'm curious!

I'm setting myself up for the possibility of driving on the continent - if I do that I'll want to fit LHD headlamps rather than mask the RHD ones.

I might get round to fitting a couple of relays at some point

I think I might do the relay mods and replace the headlamps with new ones - cleaning with IPA will only remove some of the 'road film' - it won't remove tarnish.

The car's not fast enough to need lots of light!

Valid point indeed

but the more light you have the safer it can be at any speed.

Also, not even sure if I've got a dim/dip facility. Certainly never knowingly used it.

It's built-in - switch on the sidelights and you get sidelights - then switch on the ignition and you get dim-dip as well. It was a safety feature introduced (late 70s / early 80s ? ) so you couldn't drive the car on sidelights alone.

KevR · Post by **KevR** » Fri May 28, 2010 11:22 am

electrokid wrote:
It's built-in - switch on the sidelights and you get sidelights - then switch on the ignition and you get dim-dip as well. It was a safety feature introduced (late 70s / early 80s ? ) so you couldn't drive the car on sidelights alone.

How exciting - might have to go outside and see if mine works...

As for the LHD headlights rather than masking, I've been flitting between Abroad and UK in BXs for at least ten years now, sometimes with LHD headlights in UK, sometimes with RHD headlights in France and elsewhere. I've never once masked my headlights, and I've never once been flashed for having blinded anyone with the 'wrong' dip headlight, even when I used to use white bulbs instead of the current yellow candles...
I think life's complicated enough without adding anything extra!

electrokid · Post by **electrokid** » Fri May 28, 2010 11:36 am

The simplicity thing wins for me though

I'm still not sure I fully trust those new fangled transistor things!

Keeping it simple is certainly a good thing - the 6 relay cct does the slightly more complex (replicating the original functions) using simple building blocks while improving the brightness of the bulbs.

If you want complex... some American cars in the early 70s used an automatic dip system which sensed oncoming headlamps using a photomultiplier ! ! see http://en.wikipedia.org/wiki/Photomultiplier

electrokid · Post by **electrokid** » Fri May 28, 2010 11:41 am

I think life's complicated enough without adding anything extra!

Your right - I should get out more

Mike E (uk) · Post by **Mike E (uk)** » Fri May 28, 2010 11:29 pm

Wilst you are experimenting with the lights, I can heartily recommend the dash illumination mod, so the dials are only lit when you switch the lights on.

This saves the bulbs from being replaced so often, and stops you driving off in a well lit area at night with no lights on.

If you want extra fuctionality, replace the relays with SENSEFETS then you can monitor each bulb automatically to check it is working.

A warning light or display can inform the driver which bulb is faulty.

....and then you could add some logic so if a filament fails, the other filament comes on as a get-you-home standby so you don't run with only light on one side of the car.

But car wiring is very time consuming.

400W on main beam, fat wiring + relays in new headlamp units is the way to go. Turns night into day.

BX 16V has beefy 80A alternator, which it probably does not need,unless you add more light power or a massive stereo amplifier.

Mike