DRL

On Sat, 22 Nov 2008 21:53:49 +0100, Yvan put finger to keyboard and composed:

You could use 25W or 50W aluminium clad resistors. These have an integral heatsink and mounting tabs. Farnell and RS Components stock them.

Here are two examples:

The pass transistor will get very hot (as will resistors). A linear voltage regulator is not a good idea, IMO.

I suspect that this device is not a linear regulator. IMO it would be more reliable to switch the output at 100Hz, say, with a 50% duty cycle or less, perhaps automatically adjusted for ambient conditions via a CdS photocell.

- Franc Zabkar

Why would anyone "NEED" to run drl's complete waste of time and energy. Energy being fuel and wear and tear to no purpose

Isn't there an issue with running some halogen bulbs (assuming thats what the OP has installed) at less than full power? Over time they build up a metallic coating on the inside of the glass envelope.

Nedavno F Murtz napisa:

Traffic law is about to change here. So "I must" or whatever other word is more appropriate (English is not my native language).

Nedavno Franc Zabkar napisa:

How hot do they get? I found at eBay.uk 1ohm 50W clad resistor. Would that one be OK?

Any links for this solution (the simplest variant - without automatic adjustment)?

Nedavno K Ludger napisa:

I did not hear about that. I have H1 bulbs. I'll have to search a bit to confirm that.

You got me interested so I googled and found:

"Another problem with dimming of halogen lamps is the fact that the halogen cycle works best with the bulb and filament at or near specific optimum temperatures. If the bulb is dimmed, the halogen may fail to "clean" the inner surface of the bulb. Or, tungsten halide that results may fail to return tungsten to the filament."

Years ago I pwm'ed some halogen lamps and saw evidence of the metal deposition mentioned above.

Nedavno K Ludger napisa:

Interesting reading, thank you. Perhaps I'll run bulbs at full power.

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On Mon, 24 Nov 2008 20:40:59 +1100, F Murtz put finger to keyboard and composed:

When I was in Europe 10 years ago, the law had just changed to mandate the use of headlamps during daytime, presumably as a safety measure. AFAICS, this is a pointless law, not from the energy perspective, but because people would learn to ignore them, thereby rendering them useless. It would be better to restrict the use of one's lights to indicate genuine safety issues, such as driving during rain or fog. DRLs make about as much sense as a continuously operating horn.

- Franc Zabkar

We just returned from Canada/USA where we had four different rental vehicles with DRL's. I'm quite sure all were at full brightness.

Nedavno rebel napisa:

Yes, but low or high beams?

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They're changing the law and requiring retrofit of DRLs in existing vehicles? Usually laws like that apply only to new vehicles (first registered after some date) Possibly you could cross a border and register you car there instead?

Nedavno Jasen Betts napisa:

No, new low requires you to have low beams or DRLs.

And I can not drive car registered in other countries (unless I work or live there), it is illegal here.

Nedavno rebel napisa:

I want high.

Low.

Hear Hear !! Same goes with reversing beepers at the moment trucks have them and they mostly penetrate the subconscious but as soon as every one has them you wont notice them. And fluorescent clothing same problem. All these devices only work to a limited degree until they become common. There has been studies with headlights during daytime which showed that benefits were short lived.

On Mon, 24 Nov 2008 13:52:45 +0100, "Yvan@office" put finger to keyboard and composed:

You would need to work out how much current passes through it and then compute the power dissipation using Ohm's Law.

P = I x I x R = V x V / R

If you want to reduce the operating voltage by half, then you would use a resistance equal to the resistance of your lamps at this voltage. 1 ohm seems a little too low.

If you want to reduce the operating *power* by half, then you would reduce the voltage to 70% of nominal, ie 10V. In this case a 1ohm resistor might be close.

I'd look at some DRL patents.

Try searching for "daytime running lights" here:

US patent # 3,262,011 uses a resistor to reduce the voltage to the headlamps (you can get a patent for that?).

Patent # 4,684,819 uses pulse width modulation.

Patent # 4,686,423 uses a linear voltage regulator.

As others have said, I'd be wary of operating halogen lamps at less than their rated voltage.

- Franc Zabkar

But nobody else on the road wants to se you on High

High is just as objectionable (and illegal) in the day time as in the night.

John G.

Nedavno John G. napisa:

But BMW used it originally ( but not at full power) for my car - E30 (and at least for one or two models after - E36 and Z3). Check here: