940 headlights very dim with age

[Laird Scooby]

Originally Posted by bob12

..... you should have kept it to yourself Dave No wonder this Country is finished. I am emigrating!!

Points very much taken Bob!

[mhuk]

I still not got around to playing with relays but I did put some heatsinks on those electrical boxes. Should keep them cool

[Laird Scooby]

Originally Posted by mhuk

I still not got around to playing with relays but I did put some heatsinks on those electrical boxes. Should keep them cool

They don't get warm though?

[mhuk]

somewhere it says to put in airflow and don't touch

[Laird Scooby]

Originally Posted by mhuk

somewhere it says to put in airflow and don't touch

Are you sure that isn't referring to the heatsink on the back of the bulb? I had no instructions with mine so can't comment on the actual instructions but i've not found mine gets warm at all. The heatsink on the back of the bulb can get warm though.

Theory says the chances are the ballast will get warm but like i say, mine haven't.

[mhuk]

Maybe. Well I don't need to worry about anything being warm. I not driven since it was done. Off sick with a bug

[monkeh]

Laney,
Pull the plug for the dim dip. It's in the drivers footwell, a silver looking box with a white 6 pin connector. The relay is bolted to the chassis as it gets hot.
That's the problem. That will solve it.

[bluebrickrick]

Originally Posted by mhuk

This is a reply from the seller.

As LED's don't have a half power function, they will power on fully. Here is an interesting read from one of the volvo forums about this: https://www.volvoforums.org.uk/archi.../t-201885.html

I'll look into this.

Reading this fascinating thread as both forward and rearward illumination is not brilliant with mine and thought I should comment.

While a LED does not dim on reduced voltage / current flow like most bulbs they can be dimmed very effectively by switching on and off at high frequency, on half the time - light emitted about half - unfortunately many rear and brake lamp leds seem to operate like this as standard and when traversing across the field of vision lead to a sort of dotted streak effect which makes me feel queasy - all to do with persistence of vision I think !

Although we have lost dear old Maplins (where did all that stock go ? not Ebay or Poundland !) there were kits for pulse width modulated power supplies that could offer this function that ought to be available elsewhere.

[Laird Scooby]

You're right Rick and you're describing Pulse Width Modulation - by varying the duty cycle (on time Vs off time) between 10-90%, varying degrees of brightness can be achieved.

However if your eyes are sensitive to it, as you've indicated they are resulting in nausea for you, then it's probably a good idea to disable your dim-dip if you fit a set of LED headlamp bulbs.

In practice it's hard to see any flicker on dim-dip, at least to my eyes. On normal dipped beam, non-existent.

As a finer point of operation, raising the frequency at which the PWM circuit operates can mask the flicker effect - look at a normal, domestic tungsten light bulb - this flickers 50 times a second which is why it's a bad idea to have one above a lathe or any other rotating machine as it can make the chuck appear stationary at 3000rpm in the same way a timing light makes the timing marks appear stationary on a rotating engine.

As for Maplins and their bankrupt stock, i guess it was sold off in job lots to various buyers and i've seen a few things filter through ebay and one or two other places. It's a shame they went but they seemed to have moved from their bread and butter trade of selling components and kits to the hobbyist and occasionally professional users into selling ready made high-tech consumer products, most of which wasn't wanted by their traditional customer base.
Granted much of their traditional customer base had, by its very nature, died out (literally in some cases!) but for the younger hobbyist, home inventor and so on, they still provided a much needed service.

[bluebrickrick]

My guess Dave is the automotive bulb makers are using as many common LED's as possible (I assume they are surface mount devices) and modulating the pulse width according to the required 'wattage' in any particular assemblage hence the Brake or Fogs having a visible pulse rate compared to the rears which would seem to be on a higher frequency.

I don't think there is likely to be a problem with the reflected light, it is the line of sight which is intense enough to cause a retinal effect, so not a problem to vehicle driver, just those seeing their bulbs !

Sadly I'm of an age to remember when Maplins catalogue was a double A4 Roneo'ed sheet, likewise the 'Cat' of a certain Mr Ken Whiston of Stockport, last time I visited New Mills for something, had I known it was to be the last I would have filled the boot to the headlining I particularly miss his black heat joining drive band material, nothing since has stood the test !

As you say Maplins customer base has to have changed but they were the only outlet where newcomers to the sort of interests requiring raw components could go to view and pick & choose, however, their business model allowed for such apparent anomalies as having two expensive real estate stores in Norwich, neither maximising potential - I and no doubt other 'dinosaurs on borrowed time' salute both firms for their service while trading and mourn their loss.

Rick, off 945 carcase picking this afternoon