Some important symbols for electronics students

For Android Smart Phone Wireless silicon Keyboard

How Headphone or Earphone works, working of TRS and TRRS

Introducation

In electronics, earphone jack is a family of connector typically used for analog signal, primarily for audio. It is cylindrical in shape, typically with two, three or four contacts. Three-contact versions are known as TRS connectors,

 Where

• T stands for "tip", R stands for "ring" and

• S stands for "sleeve".

• Similarly, two, three and four-contact versions are called TS, TRS and TRRS connectors respectively.

The phone connector was invented for use in telephone switchboards for switching in the 19th century and is still widely used. It is also termed an audio jack, phone jack, phone plug, and jack plug. Specific models are termed stereo plug, mini-stereo, mini jack, headphone jack, microphone jack,

        In its original configuration, the outside diameter of the "sleeve" conductor is ¹⁄₄ inch (exactly 6.35 mm). The "mini" connector has a diameter of 3.5 mm (approx. ¹⁄₈ inch) and the "sub-mini" connector has a diameter of 2.5 mm (approx. 3/32 inch).

 Modern Jack (Plug, connector)

Smart phone jack are available in two standard sizes. The 3.5 mm or miniature and 2.5 mm or sub-miniature sizes designed as two-conductor connectors for earpieces on transistor radios. All two sizes are now readily available in two-conductor (unbalanced mono) and three-conductor (balanced mono or unbalanced stereo) versions.

Four- and five-conductor versions of the 3.5 mm plug are used for certain applications. A four-conductor version is often used in compact camcorders and portable media players, and sometimes also in laptop computers and smartphones, providing stereo sound plus a video signal.

Proprietary interfaces using both four- and five-conductor versions exist, where the extra conductors are used to supply power for accessories. The four-conductor 3.5 mm plug is also used as a speaker-microphone connector on handheld amateur radio transceivers on some mobile phones. The two-conductor version with a rounded tip profile was compatible between different manufacturers, and this was the design that was at first adopted for use with microphones, electric guitars, headphones, loudspeakers, and many other items of audio equipment.

Mobile phones jack

Three- or four-conductor (TRS or TRRS) 2.5 mm and 3.5 mm sockets are common on cell phones, providing mono (three conductor) or stereo (four conductor) sound and a microphone input, together with signaling (e.g., push a button to answer a call). Three-conductor 2.5 mm connectors are particularly common on older phones, while four-conductor 3.5 mm connectors are more common on newer smartphones. These are used both for handsfreeheadsets (esp. mono audio plus mic, also stereo audio plus mic, plus signaling for call handling) and for (stereo) headphones (stereo audio, no mic). Wireless (connectorless) headsets or headphones usually use the Bluetooth protocol.

There is no recognized standard for TRRS connectors or compatibility with three-ring TRS. The four rings of a TRRS connector are assigned to different purposes by different manufacturers. Any 3.5mm plug can be plugged mechanically into any socket, but many combinations are electrically incompatible. For example, plugging TRRS headphones into a TRS headset socket (or the reverse), plugging TRS headphones or headsets into a TRRS socket, or plugging TRRS headphones or headsets from one manufacturer into a TRRS socket from another may not function correctly, or at all.

Mono audio will usually work, but stereo audio or microphone may or may not work, depending on wiring. Signaling compatibility depends both on wiring compatibility and the signals sent by the hands-free/headphones controller being correctly interpreted by the phone.

TRRS Standards

Standard	Tip	Ring 1	Ring 2	Sleeve	Phones using this Standard
OMTP	Left Audio	Right Audio	Microphone	Ground	old Nokia (and also Lumia starting from the 2nd gen), old Samsung (2012Chromebooks), old Sony Ericsson (2010 and 2011 Xperias), old Wiko (2012-)
CTIA /AHJ	Left Audio	Right Audio	Ground	Microphone	Apple, HTC, latest Nokia, latest Samsung, latest Sony (2012+), latest Wiko (2013+), Jolla, most Android phones

Notes:Nokia started to implement an universal audio connector, which enables the use of both American Headset Jack (AHJ) headsets and standard Nokia OMTP headsets.

The problem regarding to physical compatibility are:

·         If a two-conductor plug of the same size is connected to a three-conductor socket, the result is that the ring (right channel) of the socket is grounded. This property is deliberately used in several applications. However, grounding one channel may also be dangerous to the equipment if the result is to short circuit the output of the right channel amplifier. In any case, any signal from the right channel is naturally lost.

·         If a three-conductor plug is connected to a two-conductor socket, normally the result is to leave the ring of the plug unconnected (open circuit). In the days of vacuum tubes this was also potentially dangerous to equipment but most solid state devices tolerate this condition well. A 3-conductor socket could be wired as an unbalanced mono socket to ground the ring in this situation, but the more conventional wiring is to leave the ring unconnected, exactly simulating a mono socket.

Design

Examples of jack configurations, oriented so the plug 'enters' from the right. The most common circuit configurations are the simple mono and stereo jacks (A and B); however there are a great number of variants manufactured.

A.   A two-conductor TS phone connector. The connection to the sleeve is the rectangle towards the right, and the connection to the tip is the line with the notch. Wiring connections are illustrated as white circles.

B.   A three-conductor TRS phone connector. The upper connector is the tip, as it is farther away from the sleeve. The sleeve is shown connected directly to the chassis, a very common configuration. This is the typical configuration for a balanced connection. Some jacks have metal mounting connections (which would make this connection) and some have plastic, to isolate the sleeve from the chassis, and provide a separate sleeve connection point, as in A.

C.    This three-conductor jack has two isolated SPDT switches. They are activated by a plug going into the jack, which disconnects one throw and connects the other. The white arrowheads indicate a mechanical connection, while the black arrowheads indicate an electrical connection. This would be useful for a device that turns on when a plug is inserted, and off otherwise, with the power routed through the switches.
D. This three-conductor jack has two normally closed switches connected to the contacts themselves. This would be useful for a patch point, for instance, or for allowing another signal to feed the line until a plug is inserted. The switches open when a plug is inserted. A common use for this style of connector is a stereo headphone jack that shuts off the default output (speakers) when the connector is plugged in.

1.     Sleeve: usually ground

2.     Ring: Right-hand channel for stereo signals, negative polarity for balanced mono signals, power supply for power-using mono signal sources
3.     Tip: Left-hand channel for stereo signals, positive polarity for balanced mono signals, signal line for unbalanced mono signals

4.     Insulating rings

Uses

Some common uses of jack plugs and their matching sockets are:

·    Headphone and earphone jacks on a wide range of equipment. 6.35 mm (¹⁄₄ in) plugs are common on home and professional component equipment, while 3.5 mm plugs are nearly universal for portable audio equipment. 2.5 mm plugs are not as common, but are used on communication equipment such as cordless phones, mobile phones, and two-way radios.

·     Consumer electronics devices such as digital cameras, camcorders, and portable DVD players use 3.5 mm connectors for composite video and audio output. Typically, a TRS connection is used for mono unbalanced audio plus video, and a TRRS connection for stereo unbalanced audio plus video.

      ·    Hands-free sets and headsets often use 3.5 mm or 2.5 mm connectors. Phone connectors are used for mono audio out and an unbalanced microphone (with a shared ground). Four-conductor TRRS phone connectors are used to add an additional audio channel such as microphone input added to stereo output.
·     Microphone inputs on tape and cassette recorders.

·    Personal computers, sometimes using a sound card plugged into the computer. Stereo 3.5 mm jacks are used for:

·         Line in (stereo)

·         Line out (stereo)

·         Headphones/loudspeaker out (stereo)

·         Microphone input (mono, usually with 5 V power available on the ring. Note that traditional, incompatible, use of a stereo plug for a mono microphone is for balanced output)
·         LCD monitors with built-in speakers will need a cable with 3.5 mm male TRS plugs on each end to connect to the sound card.

·        Devices designed for surround output may use multiple jacks for paired channels (e.g. TRS for front left and right; TRRS for front center, rear center, and subwoofer; and TRS for surround left and right).

·        Electric guitars. Almost all electric guitars use a ¹⁄₄ in mono jack (socket) as their output connector. Some makes (such asShergold) use a stereo jack instead for stereo output, or a second stereo jack, in addition to a mono jack (as with Rickenbacker).

·      Instrument amplifiers for guitars, basses and similar amplified musical instruments. ¹⁄₄ in jacks are overwhelmingly the most common connectors. Electronic keyboards use jacks for a similar range of uses to guitars and amplifiers.

·       Some cameras (for example, Canon, Sigma, and Pentax DSLRs) use the 2.5 mm stereo jack for the connector for the remote shutter release (and focus activation); examples are Canon's RS-60E3 remote switch and Sigma's CR-21 wired remote control.

·  Some miniaturized electronic devices use 2.5 mm or 3.5 mm jack plugs as serial port connectors for data transfer and unit programming. This technique is particularly common on graphing calculators, such as the TI-83 series, and some types of amateurand two-way radio, though in some more modern equipment USB mini-B connectors are provided in addition to or instead of jack connectors. The second-generation iPod Shuffle from Apple has one TRRS jack which serves as headphone, USB, or power supply, depending on the connected plug.

·        Samsung YP-S MP3 player "pebble" uses USB-to-3.5mm TRRS jack adapter for charging as well as for data transfer.

·        On CCTV cameras and video encoders, mono audio in (originating from a microphone in or near the camera) and mono audio out (destined to a speaker in or near the camera) are provided on one three-conductor connector, where one signal is on the tip conductor and the other is on the ring conductor.

·        The Apple Lisa personal computer used a 3-conductor TRS phone connector for its keyboard.

How Three-State, Tri-State or 3-StateBuffer working in electronices

INTRODUCTION

                                                        



In electronics three-state, tri-state, or 3-state buffer logic, allows an output port to assume a high impedance state in addition to the 0 and 1 logic levels, effectively removing the output from the circuit.

                                                            OR

A tri state (bus driver) device is a device that can be active low, active high.

                                                            OR 

A tri-state buffer is similar to a buffer, but it adds an additional "enable" input that controls whether the primary input is passed to its output or not. If the "enable" inputs signal is true, the tri-state buffer behaves like a normal buffer. If the "enable" input signal is false, the tri-state buffer passes a high impedance  signal, which effectively disconnects its output from the circuit.

  Tri-state buffers are often connected to a bus which allows multiple signals to travel along the same connection.

This allows multiple circuits to share the same output line or lines (such as a bus which cannot listen to more than one device at a time).

   Three-state outputs are implemented in many registers, bus drivers, and flip-flops in the 7400 and 4000 series as well as in other types, but also internally in many integrated circuits. Other typical uses are internal and external buses in microprocessors, computer memory, and peripherals. Many devices are controlled by an active-low input called Output Enable, which dictates whether the outputs should be held in a high-impedance state or drive their respective loads (to either 0- or 1-level).

 

Uses

 

The whole concept of the third state (Hi-Z) is to effectively remove the device's influence from the rest of the circuit. If more than one device is electrically connected, putting an output into the Hi-Z state is often used to prevent short circuits, or one device driving high (logical 1) against another device driving low (logical 0).
Three-state buffers can also be used to implement efficient multiplexers, especially those with large numbers of inputs.
Three-state buffers are essential to the operation of a shared electronic bus.
Three-state logic can reduce the number of wires needed to drive a set of LEDs (tristate multiplexing or Charlieplexing).

Output enable vs. chip select

 

 

Many memory devices designed to connect to a bus (such as RAM and ROM chips) have both CS (chip select) and OE (output enable) pins, which superficially appear to do the same thing. If CS is not asserted, the outputs are high impedance.
The difference lies in the time needed to output the signal. When chip select is deasserted, the chip does not operate internally, and there will be a significant delay between providing an address and receiving the data. (An advantage of course, is that the chip consumes minimal power in this case.)
When chip select is asserted, the chip internally performs the access, and only the final output drivers are disabled by deasserting output enable. This can be done while the bus is in use for other purposes, and when output enable is finally asserted, the data will appear with minimal delay. A ROM or static RAM chip with an output enable line will typically list two access times: one from chip select asserted and address valid, and a second, shorter time beginning when output enable is asserted.

Use of pull-ups and pull-downs

 

When outputs are tri-stated (in the Hi-Z state) their influence on the rest of the circuit is removed, and the circuit node will be "floating" if no other circuit element determines its state. Circuit designers will often use pull-up or pull-down resistors (usually within the range of 1–100 kΩ) to influence the circuit when the output is tri-stated.
The PCI local bus provides pull-up resistors, but they would require several clock cycles to pull a signal high given the bus's large distributed capacitance. To enable high-speed operation, the protocol requires that every device connecting to the bus drive the important control signals high for at least one clock cycle before going to the Hi-Z state. This way, the pull-up resistors are only responsible for maintaining the bus signals in the face of leakage current.

Alternatives to a three-state bus

The open collector input/output is a popular alternative to three-state logic. For example, the I²C bus protocol (a bi-directional communication bus protocol often used between devices) specifies the use of pull-up resistors on the two communication lines. When devices are inactive, they "release" the communication lines and tri-state their outputs, thus removing their influence on the circuit. When all the devices on the bus have "released" the communication lines, the only influence on the circuit is the pull-up resistors, which pull the lines high. When a device wants to communicate, it comes out of the Hi-Z state and drives the line low. Devices communicating using this protocol either let the line float high, or drive it low – thus preventing any bus contention situation where one device drives a line high and another low.
Early microcontrollers often have some pins that can only act as an input, other pins that can only act as a push–pull output, and a few pins that can only act as an open collector input/output. A typical modern microcontroller has many three-state general-purpose input/output pins that can be programmed to act as any of those kinds of pins.
A three-state bus is typically used between chips on a single printed circuit board (PCB), or sometimes between PCBs plugged into a common backplane.
Usage of three-state logic is not recommended for on-chip connections but rather for inter-chip connections.
Three-state buffers used to enable multiple devices to communicate on a data bus can be functionally replaced by a multiplexer. That will help select output from a range of devices and write one to the bus.

Tri-state buffer: It's a Valve

A buffer's output is defined as z = x. Thus, if the input, x is 0, the output, z is 0. If the input, x is 1, the output, z is 1.
It's a common misconception to think that 0 is nothing, while 1 is something. In both cases, they're something. If you read the discussion in What's a Wire, you'll see that a wire either transmits a 0, a 1, or "Z", which is really what's nothing.
It's useful to think of a wire as a pipe, and 0 as "red kool aid" and 1 as "green kool aid" and "Z" as "no kool aid".
A tri-state buffer is a useful device that allows us to control when current passes through the device, and when it doesn't.
Here's two diagrams of the tri-state buffer.

A tri-state buffer has two inputs: a data input x and a control input c. The control input acts like a valve. When the control input is active, the output is the input. That is, it behaves just like a normal buffer. The "valve" is open.
When the control input is not active, the output is "Z". The "valve" is open, and no electrical current flows through. Thus, even if x is 0 or 1, that value does not flow through.

Here's a truth table describing the behavior of a active-high tri-state buffer.

c	x	z
0	0	z
0	1	z
1	0	0
1	1	1

Why Tri-State Buffers?

We've had a long discussion about what a tri-state buffer is, but not about what such a device is good for.
Recall (from earlier) that a common way for many devices to communicate with one another is on a bus, and that a bus should only have one device writing to it, although it can have many devices reading from it.
Since many devices always produce output (such as registers) and these devices are hooked to a bus, we need a way to control what gets on the bus, and what doesn't.
A tri state buffer is good for that.
Here's an example:

There are three devices, each of which output 32 bits. These devices have their outputs hooked to a 32 bit bus.
We want to prevent more than one device from writing to the bus. Ordinarily, these devices always generate output, so we're in trouble merely by attaching more than one device's output to the bus.
As long as at most one of the following control bits, c₀, c₁, c₂, is 1, the bus is fine. That is, the bus will not have two devices attempting to write to it at the same time.