# Tag Info

96

You are right, in a sense. These sensors do need moving components. However, they are a chip on your board. Tiltsensors (actually, accelerometers), and gyroscopes (and pressuresensors, ...) are part of a family called MEMS: Micro-electromechanical systems. Using similar techniques as already common in integrated circuit fabrication, we can make amazing ...

24

Simply because having more bands not only requires a very versatile chipset, but also extensive antenna design! To explain: It's impossible to make the perfect antenna for all frequencies, but you can make "compromise" broadband antennas. You can do that in a lot of ways, but in the end, you need to integrate those into a mobile device. And that's where it ...

22

I assume that you have a GSM phone. When the GSM protocol was developed, they overlooked the fact that a "frame rate signal" in the protocol caused modulation of the RF signal at a consistent audio frequency rate with very clean consistent periods with and without RF. The GSM system was so important and so much had been spent on it that the allowed this ...

20

what is it that makes it possible for cellular networks to keep getting faster Basically, good old Moore's law. The handset is only half the equation. More modern and powerful silicon does help in getting better channel quality, less noise, etc. However this can't go above the channel bandwidth as per Mr. Shannon. A simple way to boost the bandwidth ...

18

Headphone jacks have extra contacts inside, which act as switches. The the drawing below, pins 4 and 5 are intended for sensing that the plug was inserted. They are not intended for audio signal. When the plug is not present, the switche, which are formed by 2 & 4 and 3 & 5, are closed. When the plug is inserted, these switches are open. The ...

16

The sensory device is a weight on a spring. It is indeed "small-scale motion of some tiny components of the sensor", and it's also "another chip on a circuit board". The key word here is MEMS. It's possible to build small silicon structures and then etch away underneath them, leaving a free-floating piece. If the piece is long and thin, it will deform ...

15

Most modern phones have a charging control circuit which takes care of what you are proposing. When the battery is charged, the charge control IC will terminate charging of the battery, then monitor to see if it needs charging again. So all the charger has to do is make the power available. Below is a flowchart from the datasheet of MCP73831 Li-Ion charge ...

15

So I did some research and found out that there's a recent advance in battery technology that allows LiPo cells, used in both mobile devices and hobbyist/RC applications, to operate at higher voltages. Specifically, a silicon-graphene additive is used in the anode to protect against corrosion at higher voltages, allowing them to be charged to 4.35V or even 4....

14

On Android phones, on iOS devices, and on HD Audio PCs, no mechanical switches in the socket are used. Instead, the headphone socket has 4 contacts instead of 3, and accepts both 4-contact headsets and 3-contact headphones. The sleeve of the 3-contact headphone audio jack connects two of the socket contacts together. One of the contacts is responsible for ...

14

Usually just marketing Most aftermarket batteries are labelled in way that is extremely optimistic (if not an outright lie). It is possible to change chemistries to go to one with a higher energy density, but this is usually very unsafe as the phone's internal battery charge regulation circuitry is not tuned for the new chemistry and can cause a fire or ...

14

There's no general answer. First of all, you have a misconception about GSM, 3G, 4G: The frequency bands you list are some of the frequency allocations for these networks. These are different between different operators and in different countries. Then: Cellular networks are not broadcast transmitters. They don't work with constant output powers. The ...

12

I call quackery. You don't want to shield the electromagnetic field, because that's what makes the phone work. If you would stop the EM field you wouldn't have communication. The "24 carat gold" should also ring a bell. I bet there's not a $\mu$g gold in it. Even if you want to make a shield there are much cheaper materials which perform almost as well ...

11

Your connection to the cellular network, no matter the "G", always uses the same antenna. You can see this in a teardown of whatever phone you have. For instance, here is a teardown of my phone: HTC Thunderbolt Teardown In the last photo, you can see that the LTE and EVDO antenna is one and the same. This also handles your 2G connections as well even ...

11

Looks like a "0 ohm resistor" (a jumper in some standard size such as 0603). From Yageo's catalog:

11

It is resistor. It's value is 0 ohm, so neutral to the trace. It is used in place of a jumper or wire to bridge two traces while allowing a few features. It can easily replace (or be replaced by) an actual resistor, if it was added then decided that the resistor was not needed. It allows a second signal to pass underneath. And it can be used for ...

11

This can be false marketing. This can also be more or less true and here's how. First, battery technology slowly advances. One major power tools producer launched its 10.8 volts line of professional power tools in perhaps 2004 and they shipped with batteries assembled of 1Ah Li-Ion cells. In perhaps 2007 they switched to 1.3 Ah cells of the same size. Later ...

11

I think following are some of the key technologies/techniques driving up cellular data rates. Move to higher carrier frequencies where wider bandwidths are available. Soon we will have millimeter wave technology being used in cellular. Multi Input Multi Output (MIMO) Antenna systems allowing parallel transmission of data streams. Advance modulation ...

10

Take a look at the specifications of Neo FreeRunner (schematics available) to see what is involved in a cellphone. Basically you need: CPU and its associated circuitry (to drive a display, receive touchscreen events etc...) RF and baseband circuitry; design circuit boards, antenna etc... other hardware (Bluetooth, Wi-Fi, GPS etc...) writing software to make ...

10

Yes, but there's a problem: that same radiation that may be harmful is what the phone needs to communicate with the network. You can't separate the two. So no harmful radiation = no communication.

10

Such chargers1 are (at least, supposed to be) basically just constant-voltage supplies, i.e. whenever connected to AC power they should offer the specified voltage, no matter if a device is already connected. For a modern switching power supply, there's quite a lot of circuitry included that makes sure this goal is met pretty reliably, so indeed you don't ...

10

There is a charge controller chip inside the phone that determines how much current to put into the battery. Generally lithium ion batteries are charged with a constant current until the cell voltage reaches a specific level, at which point the charge controller switches over to constant voltage charging until the current drawn by the cell decreases to zero....

10

Theoretically, yes, a phone or tablet could work just as well in say the International Space Station (ISS) as it does here on the ground. Let's break this down a bit. There are two types of motion a device needs to detect. Linear Motion Self-contained accelerometers use the deviation of a spring-coupled mass from a normal rest point as a measure of ...

9

I guess you're supposed to stick it onto your cellphone, and that's supposed to protect you from nasty E-M radiation. Electromagnetic radiation can be nasty at some energies, but the EM radiation from your cell phone isn't dangerous. Radiation is dangerous as such when it is ionizing radiation - capable of removing electrons from an atom, creating an ion. ...

9

Feasible: yes Useful: no, because the power needed by a smartphone is orders of magnitude larger than what such a (kinetic) generator generates. A (non smart) wristwatch needs only very little power, it can run for years on a small button cell. This amount of power can easily be generated by a kinetic generator. A smartphone has a large battery and needs ...

9

All the comments and answers are great to help you understand how it is possible. But, here's something that will help you understand how it's actualized in real products. (image source) This is a tiny IC (3x3x1 mm!) by InvenSense. It has a three-axis accelerometer (for lateral movement), a three-axis gyroscope (for rotation), and a three-axis ...

8

A device (phone) gets charged at optimal (high) rate only when it recognizes "charging port signature" on charger side. For Type-A port, there are several DIFFERENT port signatures that a charger port can provide: USB Battery Charging v1.2 Dedicated Charging Port, where D+ and D- are floating but tied together; USB Battery Charging v1.2 Charging Downstream ...

8

For storage purposes, a Li-ion battery should be charged to 60-70% capacity. This reduces the damage done to the electrode material over time while still allowing enough charge so that it will hopefully not be completely discharged due to self-discharge when you get around to using it. For charge cycle purposes, a Li-ion battery should be charged during its ...

8

Short answer: external antennas are unattractive to the user. The consumer drives the market, and these days, consumers want thinner, lighter, faster, etc. This is actually a huge problem for antennas because the physics are fundamentally limiting. Most antennas in cell phones are some sort of variant of a PIFA (planar inverted-F antenna). Antenna-Theory ...

7

One of the most popular items on Sparkfun is 128x128 Nokia Color LCD screen. The protocol has been reverse engineered by various people and libraries made for Arduino and other platforms. In general, if the screen has only a few pins, it's likely to have a built-in LCD controller and use SPI or I2C for the protocol. Such protocols are usually not very hard ...

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