7,670 reputation
11230
bio website embedinc.com/olin
location Littleton, Massachusetts
age 58
visits member for 2 years, 2 months
seen 4 hours ago

Electrical engineering consultant specializing in microcontrollers and the circuitry around them. Master of engineering in EE from Rensselaer Polytechnic Institute in 1980.

We are certified Microchip design partners, and have been in the top catagory consistantly since around 2000. Various free downloads related to developing PIC firmware and other things are available at http://www.embedinc.com/pic/dload.htm.


Apr
13
comment Earth curvature refraction for dummies
@David: I don't know if just the normal vertical pressure drop is enough to account for that, but together with specific atmospheric effects it sounds possible. It would help to define the geometry of your particular test case better, how high each of receiver and transmitter were locally, how high the intermediate terrain, etc. Then we can compute how much deflection is actually required to explain it. The data should be in your question. No, I'm not going to watch some video you linked to.
Apr
11
comment What will be the content of mercury of a can which contains 100 gm water?
0, obviously. The can contains water according to the specification, with no mention of mercury made. Either someone was trying to see if you're awake, or this is just a really dumb question.
Feb
26
comment Why is my breath hot when i open my mouth all the way, but cold if I blow like a whistle?
@rjmess: You can think of it various ways, which ultimately should lead to the same result. Viscosity is one way to think about it. Bernoulli's principle is another.
Feb
26
comment Why is my breath hot when i open my mouth all the way, but cold if I blow like a whistle?
@rjmess: "Ambient" means the stuff that is all around. In this case you can take ambient air to mean the not-breath air.
Feb
23
comment Can an object appropriately isolated from its surroundings become colder than its surroundings?
@Anthony: Yes, that would be interesting. Unfortunately, I don't have details. I only remember reading somewhere years ago that the ancient Egyptians used a method like this to make ice at night even when the air temperature was above freezing. It helps to be in a desert where the air is clear and the sky often cloudless.
Feb
21
comment Where do the electrons go?
It's all a big scam. The power company charges you for electrons they suck back on the next 1/2 cycle. What a racket! They sell you the same thing over and over again.
Feb
12
comment Why can't I get a output lower than 0V in this circuit?
Voltages are always between two points. Saying the green signal is at the left side of the cap without a reference is non-sensical. I'll assume you mean the bottom node to be the implied 0V reference. Also, you should be able to see for yourself that the text from the diode and the voltage source are obscuring each other. Science requires attention to detail. -1 for the sloppiness.
Feb
10
comment Minimum Distance for “Speed of Light Approach”
There is no such distance. As the speed of the test mass gets approaches the speed of light, its mass increases. More and more of the additional potential energy will be converted to mass instead of speed as the speed gets closer and closer, but never reaches, the speed of light.
Feb
3
comment Might a planet perform figure-8 orbits around two stars?
Two stars that stay at a fixed distance from each other must be orbiting each other.
Feb
3
comment Is there something equivalent to a diode for light?
No, a ideal diode doesn't consume any power. It is simply a one-way valve for current, which doesn't require any external power to operate. Some specific implementations do take external power, but that's a engineering issue.
Jan
30
comment Wavelength of X-rays in a tube
Actually, the wavelength of xrays produced is a function of the energy electrons have when hitting the anode. Perhaps you are seeing secondary re-emissions?
Dec
25
comment Why is concrete dry around cracks?
@Foris: That's a good idea. There is not water outlet anywhere near there, but I'll see what I can come up with next summer.
Dec
25
comment Why is concrete dry around cracks?
@Floris: It's winter here now. I think this is a summer phenomenon, so it'll be some months before I can collect more data. Short rain squalls with heavy drops are not that unusual, but they come without warning, and for best results it seems I need to photograph it within 2-3 minutes. I'll try to be vigillant next summer, but it's not certain I'll catch anything good.
Dec
24
comment Why is concrete dry around cracks?
@Brandon: But the effect can be seen some distance from the crack, a few inches in some cases. Also note that the entire effect happend in about 3 minutes, maybe 5 by the time the picture was taken.
Dec
24
comment Why is concrete dry around cracks?
No, this is definitely not it. See my point #3 in the question. There was never enough water on the ground at any time to flow. Also, selective dryness due to water flowing into cracks looks quite different. The dryness is only on the downhill side of each crack. Note the dry areas in the picture surround the crack on both sides about equally and regardless of crack orientation relative to slope.
Nov
19
comment Car driving / falling off of a cliff - will it land upright?
I don't think it really matters much where the center of gravity is relative to the two axles. No matter where it is, you get the same net torqe impulse from the back wheels being pushed up while the front wheels have already gone over the edge. This is where the rotation comes from. Center of mass relative to shape will eventually dictate what happens due to air resistance, but I'd say that is minimal in a 1/2 to 1 revolution fall for a typical car or van.
Nov
19
comment Car driving / falling off of a cliff - will it land upright?
The speed effects the net torque impulse imparted during the time the front wheels are over the edge but the back wheels not yet. This effects the rotation speed, which in turn effects the fall distance for one complete revolution.
Oct
30
comment Can you pre-determine the result of a coin toss?
You left out air resistance, which I suspect has some impact on the outcome.
Oct
29
comment Silicon/silicon dioxide interface
You seem to be confusing a semiconductor junction with bulk semiconductor material. Photocells work like what you describe, but only when the photon hits in a semiconductor junction. The principle doesn't work in bulk semiconductor material, whether doped or not.
Oct
29
comment Bungee jumping - find spring constant
@Floris: I don't know, as that would require actually reading your answer. I saw a bunch of equations and "harmonic oscillator" mentioned in your first sentence, so thought I'd give a simpler answer.