How does a GPS work?

I try and challenge myself when I am in unfamiliar territory to figure out where I am and how to get home. I did this last Friday and miraculously made it all the way home. This being said, I do always have a GPS in the car with me, whether it be my actual four year old GPS or something that refuses to talk to me, like say, an iPhone. Why won't it say something to me? I can't read a map while driving Steve! Anyways, I guess what still bothers me is; how does it work? 

I asked Ben.

There are two parts to GPS (Global Positioning System): the satellites up in space and the receiver in your hand (e.g. your GPS enabled smart phone).

There are a whole bunch of GPS satellites (Wikipedia says 31) so that at any point in time, on any point on earth, at least 4 of them are in the sky overhead.  Each satellite carries a ridiculously accurate atomic clock and basically just sits in orbit constantly transmitting the time and its exact location in orbit.  

So if, for example, you are in an unfamiliar city and you are in an emergency situation where you absolutely must find the location of the nearest frozen custard shop, then all you have to do is pull out your smart phone, which is a GPS receiver.  The receiver also has a very accurate clock (although not as accurate as the satellites have) and it establishes a link with as many satellites as possible.  Then it compares its own time to the time that each of the satellites is broadcasting.  Since the signal has to travel through thousands of miles of space, the time broadcast by the satellites is going to be a little bit behind the time that the receiver is keeping.  The receiver uses this difference in time along with a little bit of math to calculate how far the broadcast signal has traveled, and thus how far away each individual satellite is.  At that point, the receiver knows the exact orbital location of several satellites and exactly how far away each one of them is, and it uses that information to triangulate its position.  To get a location that is accurate enough to be usable the receiver has to calculate out to 7 or 8 decimal places, so it's pretty heavy stuff.

Are Cylons Possible?

I'm going to put this out there for the world to know. I LOVE BATTLESTAR GALLACTICA. I want to watch the entire series again, very soon. So my question for the day is... Are Cylons possible? 


How did you find out about my research?


Within our lifetime I have no doubt that we'll see robots that look and move like humans, but I'm not sure about artificial intelligence.  Back in the 80s everyone thought it was only a matter years before we would have machines that could carry on a full conversation with a human, but here we are some 30 years later and the best we have is this: http://shitthatsirisays.tumblr.com/

What's that copper wire hanging down from our light?

We recently replaced our dining room light.. it looks great, thanks for asking! During this process I noticed a wire that the designer in me wanted gone. So why is it there and what is it?

Ben, what is that copper looking wire hanging from our light?

That's the ground wire and it's there for your safety.  Lighting fixtures (as well as any appliance with a metallic chassis or housing) have three wires: one that's black, one that's white and one that's either green or bare.  The black wire is Hot, which means that it has 120VAC on it.  Don't touch that one.  The white wire is Neutral which is the return path for the circuit in question and it is at ground potential, which means there isn't any voltage on it.  The green or bare copper wire is the ground wire which is attached to the metal enclosure and is connected to ground.


Without a ground wire, if the black wire comes loose and touches the metal enclosure, then the whole enclosure is sitting at 120 volts so if you touch it you get a new hairdo.  However, if you properly connect the ground wire then if the black wire touches the (now grounded) metal enclosure, then the grounding wire creates a short circuit to ground which will trip the breaker so that there is no shock hazard.  It's not as exciting, but nobody dies so it's sort of a tradeoff.

Ding Dong. How does the doorbell work?

In my efforts to help clear things up for the kids visiting the Bruckner residence on Halloween, I took the doorbell off our house. Why you ask? Because it was dead and I didn't want kids freezing to death thinking it had worked. Anyways, it's replaced now and I wanted to know how it works. So I asked Ben, and guess what? He knows: 

Traditionally, there is a small transformer located somewhere in your house that converts the 120VAC down to 24VAC, and that lower voltage is connected to a wire that runs to the front door and is attached to your doorbell button. The other side of the doorbell button is then connected to some sort of audible bell, which is then in turn connected to the other side of the doorbell transformer, completing a circuit.  Normally, the doorbell button is basically an open switch so no current is flowing and nothing is happening.  But when someone presses the doorbell button it closes a switch that completes the circuit and current flows into the bell sounding unit.  I'm not sure what they are usually comprised of, but I would guess some sort of solenoid that strikes one bell when the circuit is activated (ding), and then when the doorbell button is released, a spring pulls the striker back and hits another bell (dong).

An alternative method is to have a small battery powered wireless transmitter inside the doorbell button that communicates to a wireless receiver in side the house that is connected to a speaker. The advantage of this approach is that you don't have to run any wires. The disadvantage is that at some point the batteries die out and then the Chinese food delivery guy just stands outside your door hitting a button that does nothing and then waiting for you to notice that he's there while you starve to death inside.