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Type: Posts; User: dougmc; Keyword(s):

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1. ## Thread: How many Lumens do I need?

by dougmc
Replies
55
Views
5,526

### No. Lux will just tell you how bright one spot...

No. Lux will just tell you how bright one spot is, typically the very brightest spot, in the middle of the bright spot made by the light.

But that depends on how far the surface is from the light...
2. ## Thread: How many Lumens do I need?

by dougmc
Replies
55
Views
5,526

### They're related, but they measure different...

They're related, but they measure different things.

Lumens measures total light (adjusted for how sensitive the human eye is to each wavelength of light, but we can generally ignore that part.)
...
3. ## Thread: Moore's laws for lights?

by dougmc
Replies
29
Views
1,411

### I didn't say or even imply that it did. I also...

I didn't say or even imply that it did. I also invoked the largely tongue-in-cheek suggestion that number of blades in a razor blade might follow a similar progression, to further suggest that it...
4. ## Thread: Moore's laws for lights?

by dougmc
Replies
29
Views
1,411

### The whole thing is one big heat sink, and it's...

The whole thing is one big heat sink, and it's likely used with a 15+ mph or so breeze blowing on it (i.e. you're riding.) It probably wouldn't get excessively hot unless you stopped for a few...
5. ## Thread: Moore's laws for lights?

by dougmc
Replies
29
Views
1,411

### 8.4 volts is certainly right for a fully charged...

8.4 volts is certainly right for a fully charged 2s battery.

As for plugging in an ammeter ... that would require that somebody actually buy this monstrosity. But 1 amp on high is probably too...
6. ## Thread: Moore's laws for lights?

by dougmc
Replies
29
Views
1,411

### Let's look at this another way ... One amp at...

Let's look at this another way ...

One amp at 8.4 volts is 8.4 watts. 3000 lumens/8.4 watts = 357 lumens/watt, which is significantly higher than the theoretical limit for a white LED, and...
7. ## Thread: Moore's laws for lights?

by dougmc
Replies
29
Views
1,411

### This light/USB charger is the worst example of...

This light/USB charger is the worst example of lumen inflation I've ever seen -- they claim 2300 lumens, but the reality is perhaps 10 to 15 lumens.

That said, given that it's often on sale...
8. ## Thread: Moore's laws for lights?

by dougmc
Replies
29
Views
1,411

### 3000 lumens tends to mean around 30 watts, and...

3000 lumens tends to mean around 30 watts, and six 3000 mAh 18650 cells could produce 30 watts for about 2.25 hours. To get four hours out of it, they'd have to reduce the lumens somewhat or be...
9. ## Thread: Moore's laws for lights?

by dougmc
Replies
29
Views
1,411

### Moore's laws for lights?

First we had Moore's laws for CPUs, where number of transistors increased exponentially, then it was hypothesized that it might also apply to razor blades ... but is it beginning to apply to bike...
10. ## Thread: Day Time Running Lights

by dougmc
Replies
59
Views
1,672

### The Planet Bike Blaze 2w? It's on the high end...

The Planet Bike Blaze 2w? It's on the high end of "be seen" lights and the low end of "help me see" lights.

I don' t know why you don't trust them, but the quality on this specific light is good...
11. ## Thread: Farmers Branch, Texas LEO

by dougmc
Replies
64
Views
3,162

### But you told us that you didn't stop. Right? Or...

But you told us that you didn't stop. Right? Or are you going to tell the judge something other than what you told us? (Well, the original poster said he didn't stop, not you.)

And as Coal...
12. ## Thread: Farmers Branch, Texas LEO

by dougmc
Replies
64
Views
3,162

### While it's true that most people do rolling stops...

While it's true that most people do rolling stops when there's not traffic to yield to ... the law requires a complete stop.

So when you show up to contest the ticket, you can either go "Well,...
13. ## Thread: Day Time Running Lights

by dougmc
Replies
59
Views
1,672

### That must be specific to whatever lights you've...

That must be specific to whatever lights you've got -- in general, flashing modes use the battery up considerably slower than steady on modes, for example this light lasts 5 hours on high, 12 hours...
14. ## Thread: So there's this Boston cabbie who gets arrested...

by dougmc
Replies
51
Views
2,160

### Bail is not required when somebody is sued --...

Bail is not required when somebody is sued -- that's a civil case.

Bail is only for criminal cases, and in general only for the more serious ones -- moving violations may be a criminal matter in...
15. ## Thread: How much is 6 watts?

by dougmc
Replies
22
Views
1,204

### The small difference is largely due to how power...

The small difference is largely due to how power needed to overcome air resistance is proportional to speed cubed, and at speed most power goes into overcoming air resistance. Because of that,...

by dougmc
Replies
767
Views
161,994

### Sticky: After seeing the \$15 one, I ordered another. It...

After seeing the \$15 one, I ordered another. It arrived yesterday ... which had it arriving in two weeks.

Things I've ordered from China in the last year or so are getting here more quickly...
17. ## Thread: Autonomous cars and cyclist salmon.

by dougmc
Replies
132
Views
4,608

### If you just lose your alternator, sure. If you...

If you just lose your alternator, sure. If you lose your water pump (which you normally do when your car only has one belt) ... most cars will overheat (which tends to mean expensive damage if you...

by dougmc
Replies
767
Views
161,994

### Sticky: Well, except that the title was "Black Solarstorm...

Well, except that the title was "Black Solarstorm 5000LM 2X CREE XML U2 LED Front Bicycle Bike Headlight Headlamp | eBay".

Usually "lumens" are abbreviated "lm" rather than "LM", but beyond that...
19. ## Thread: Autonomous cars and cyclist salmon.

by dougmc
Replies
132
Views
4,608

### There is an electric motor connected to steering...

There is an electric motor connected to steering system, and so is your steering wheel. If you lose power, you can still steer, though with considerable effort.

However, if the circuit/computer...
20. ## Thread: Autonomous cars and cyclist salmon.

by dougmc
Replies
132
Views
4,608

Don't you already? Your car already has microprocessors and such that if they failed in the wrong way could end your life. The "runaway throttle" problems that some cars have had have been computer...
21. ## Thread: Autonomous cars and cyclist salmon.

by dougmc
Replies
132
Views
4,608

### I do realize that you're attempting to engage in...

I do realize that you're attempting to engage in some clever word play here, but just to be clear, I was using the term "imagine" in the second way here --

Now, it is indeed a forward looking...
22. ## Thread: Autonomous cars and cyclist salmon.

by dougmc
Replies
132
Views
4,608

### I imagine that ultimately the self-driving cars...

I imagine that ultimately the self-driving cars will *still* handle that better than a human -- they'll see the car move a tiny amount before it backs up and anticipate that it might back out...
23. ## Thread: 3 Foot Law. Read and save to your phone. Cops will not argue with you on this one.

by dougmc
Replies
10
Views
1,013

### Cops usually won't argue with you on *any one*,...

Cops usually won't argue with you on *any one*, not just this one.

That said, sometimes they'll respond favorably to being shown the exact wording of the law -- but I'd expect most of them to get...
24. ## Thread: Having bottles thrown at you while you are cycling.

by dougmc
Replies
147
Views
8,524

### And here's what happens when the police take a...

And here's what happens when the police take a charge of 'he threw a bottle at me' too seriously.
25. ## Thread: Vitriolic response to biking event

by dougmc
Replies
19
Views
885

### That's an odd article. The title suggests that...

That's an odd article.

The title suggests that this was an experiment, and that it failed and now it's over and won't be revisited. They don't use the world failed, they just say the experiment...
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