Single stage amplifiers for telephones

A power amplifier circuit arrangement particularly useful for portable phones used in wireless systems. A power amplifier stage can be partially or completely bypassed so that multi-stage amplifiers can be built that allow wide dynamic range of power amplification to be obtained efficiently. A switch at the input of an amplifier stage couples an input signal either to an amplifier or to a bypass path. The output of the amplifier is coupled to a first impedance-transforming network.

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Content:

• Technical Specifications
• Simple Telephone Amplifier Circuit
• The application of junction transistors to audio-frequency telephone line amplifiers
• Partial or complete amplifier bypass
• Best headphone amplifiers 2021: budget and premium
• Electrical Engineering (ELG)
• Telephones at Home
• Headsets 101: Ultimate Guide to Understanding Headsets
• QSC in Action
• US2885483A - Telephone instrument utilizing transistor amplifier - Google Patents

WATCH RELATED VIDEO: Single Stage Transistor Amplifier/ Small signal BJT Amplifier - part 1

Technical Specifications

Headsets have become commonplace in our new iWorld of technology. With so many choices, applications, plug-ins, adapters and options…where do you begin? Our HEADSETS Guide will explain headsets in detail with numerous pictures to help you visualize which devices and cables you need, where and how they connect, along with anything else you need for the perfect headset solution. We will be updating the guide often as technology changes in our complex world of headsets for your office, home, mobile, and computer.

Click on the choice below which best describes your headset need:. With hundreds of telephones available on the market, you will find three typical methods used to plug a headset into a telephone: 1 Many older phones and more basic phones will require an amplifier that plugs into the handset port on your telephone.

To have a corded commercial grade headset solution you will need two items; the headset and either an amplifier or a quick-disconnect bottom cable. This connection allows you to leave your headset on at all times and quickly disconnect from the amplifier, or bottom cable, when you need to walk away from your desk. A quick disconnect is made to be pulled apart and re-connected an endless amount of times without ever wearing out.

Many first time commercial grade headset users assume you only need to purchase a headset , not understanding amplifiers and bottom cables. As you can see by the picture, buying only a headset will result in immediate frustration because your headset will not have anything to plug into. To connect your headset to your telephone, you also need an amplifier or bottom cable, depending on your phone. They provide a mute switch, speaker and microphone volume adjustment, and give the highest possible call quality available.

To Help with Compatibility — We have put together the following quick reference guides for the most popular phones:. An amplifier Plantronics M22 pictured is a piece of equipment that sits between the headset and the phone.

The amplifier plugs into the phone jack where your telephone handset receiver currently plugs in. Your handset then plugs into the amplifier so when the amplifier is on, your headset is active. When the amplifier is off, your handset receiver is active. On older phones you will need to remove your handset and set the handset to the side of your phone to establish a call.

When finished, you will need to replace your handset to hang up the call. This is because you need to raise and lower the switchhook lever located under your handset ear piece to get a dial tone and hang up calls. Changing to a different amplifier or manufacturer will not change the fact that you need to raise and lower your handset for each call.

Amplifiers have speaker volume and microphone volume, compatibility settings for your specific phone, and a mute button. AA batteries are included to power the amplifier. Batteries typically last six months to two years, depending on use, and will beep in your ear during calls when the batteries are low. Finally, an amplifier will come with two cords.

Many newer phones allow the use of a Direct Connect cable A10 pictured to plug into a headset port. With a Direct Connect cable, you are relying on your telephone to provide adequate speaker and microphone volume. It is imperative that you check a compatibility guide or consult a headset expert to determine if a Direct Connect Cable is an option and which one would be best. There are currently different cables with different wiring and volume levels.

A Headset Amplifier or Direct Connect Cable is required, which plugs into your telephone using a hard plastic, modular connector called an RJ9 headset jack which is equal to and also called RJ22 headset jack. This jack or modular plug can be clear or smoke colored. RJ9 wires carry audio, so you can talk and listen to callers. RJ11 carries higher voltage, tip, and ring, so your phone rings when a signal is received, you get a dial tone so you can initiate calls, and you get audio so you can hear the caller.

A few telephone manufacturers have opted for a 2. Unfortunately, this is both good and bad. The bad is that some business users will make the mistake of purchasing a home-use quality headset with a 2. A commercial grade headset can still be used when your phone has a 2. You have two options:. Option 1 — Use an amplifier for complete volume control preferred method.

When it comes to selecting a headset , your environment and personal wearing style are the two factors to consider. The microphone on a Noise-Canceling headset makes your voice clearer to your caller. A Noise-Canceling headset has a microphone boom, and the actual microphone electronics are located at the end of the boom.

The front side of the microphone targets your voice, and the back side of the microphone picks up and dampens any background noise. The headset focuses on emphasizing your voice and reducing the background noise. Many headset users working from home are hoping if they purchase a Noise-Canceling headset it will hide the dog barking or baby crying in the background.

Newer high-end headsets are starting to have the engineering to remove the dogs barking and babies crying. This technology also work well in loud call centers with hundreds of users all in close proximity. Truly amazing! Most headset s come in both Noise-Canceling and Voice-Tube models, so you can base your purchase decision on your environment without compromising on style.

If you hear background noise, you need Noise-Canceling …if not, save a few dollars with the Voice-Tube headset which will also sound better in the quieter environment. Microphone positioning. If you are using a voice-tube model, Plantronics recommends replacing your voice-tube every six months to ensure the best possible sound quality to your callers. This is a good rule of thumb, but it really depends on how well you take care of your headset.

At the end of a voice tube is a very fine, wire screen that keeps the tube clear from obstruction. If you eat while wearing your headset , small food particles will always find their way to the end of the tube, covering the screen and reducing your voice volume.

Similarly, if you wear makeup, it can clog the screen. In these scenarios, you may need to replace the voice tube more often than every six months. From experience, cleaning rarely works and usually only packs the obstruction further into the screen, which reduces your voice more.

When choosing how you want the headset to fit, your personal preference is key, but your environment will also play a part in the decision. In extremely loud environments, covering up both ears is best.

Also consider how you interact with co-workers. If you need to completely focus on your caller, covering up both ears binaural is optimal to block out noise around you. Over-the-Ear headsets are much smaller, lighter weight and more discrete than Over-the-Head headsets. This is where your personal preference will ultimately decide which headset to choose. Headsets are not ear specific and you can easily switch the headset to fit either ear.

Binaural both ears covered headsets can be worn with the microphone on either ear. A convertible headset comes with multiple wearing styles and allows you to find that perfect fit. A convertible headset is also beneficial in an office where people share headsets with different wearing preferences, because you can quickly and easily change to the style you prefer for your shift.

With corded headsets , there are a few headset accessories that will make your life easier. First are leatherette ear cushions which slide over your hair, making your headset slide on and off faster without getting tangled in your hair; the standard foam cushions have a tendency to tangle with longer hair.

Next is a Y-cord for training. When you hire new staff or simply want to monitor existing staff for coaching, the Y-cord lets you listen into calls and take over calls when needed. Was this helpful? If so please share with others to help them with their headset needs!

On most telephones, you will plug into your handset port. To operate, you first push the button on the side of the headset, known as the Call Control Button to turn the headset on. Next, you will lift your handset and set it to the side of your phone.

This will either connect you to your caller or provide a dial tone to then start dialing on your telephone. Once a call is established you have the freedom to roam your office while you talk. When finished with the call, place your handset back in the cradle to hang up your call and push the Call Control Button to turn your headset off.

Some users prefer to leave the headset on at all times to simplify the procedure, but make sure your battery time is sufficient for having the headset on at all times.

See 2 and 3 for remote Answer and Hang Up information. If you have a telephone with a headset port, you will push the button on the side of the headset, known as the call control button, to turn the headset on.

Next, press the ringing line for an incoming call or press an available line to make an outbound call and begin dialing. When finished with the call, press the Headset Button on your telephone to release the call and push the Call Control Button to turn your headset off. An important concept to understand is if you are plugging into the headset port, you will not be able to answer or hang up remotely. There are LED lights on the base to indicate power, charging and other features. Wireless units give you freedom, and adding a Handset Lifter or EHS cable allows greater productivity by allowing you to answer and hang up remotely.

Both will sense when your phone is ringing and generate beeps in your headset to alert you of a call. If you choose to take the call, simply press the Call Control Button on your headset to answer the call. Your phone answers the ringing line and you begin talking. When finished you press the Call Control Button again to disconnect the call. You will need to return to your phone to press the appropriate buttons to dial, transfer a call, or to perform any other phone functions.

The EHS electronically establishes calls on newer phones without the mechanical motor and physical movement of your handset, but otherwise accomplishes the same thing. Having the ability to answer remotely greatly increases your productivity. You can answer away from your desk and carry on conversations where ever you need to take them. It also allows you to answer calls that would have normally gone to voice mail. This saves you a tremendous amount of time playing phone tag with customers or co-workers.

Simple Telephone Amplifier Circuit

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The application of junction transistors to audio-frequency telephone line amplifiers

If you're spending big on a pair of premium headphones , a dedicated headphone amplifier will make them sing much more than if you were to simply plug them into a computer, phone or even, depending on the quality of its built-in headphone amp, a hi-fi component. So what should you look for in a headphone amplifier? Analogue inputs mean you can plug in a traditional source, such as a CD player, but more modern amps boast digital inputs and a built-in DAC for broader compatibility — ideal if you're listening to music stored on a computer, say. Size and portability are also key considerations. Some of the below will happily slip into a jeans pocket and, with the right cables and connectors, can even be paired with a mobile phone. Other models command that you clear your desk. So, decide whether you'll be listening to your headphones on the move or solely at home. We've rounded up the best headphone amplifiers money can buy, including the top budget, mid-range and high-end options. Not only is the Award-winning soundKey a fantastic piece of kit, it's highly affordable too. A killer combination.

Partial or complete amplifier bypass

In earlier days, before the invention of electronic amplifiers , the coupled carbon microphones are used as crude amplifiers in telephone repeaters. The first electronic device that practically amplifies was the Audion vacuum tube, invented by the Lee De Forest in the year The term amplifier and amplification are from Latin word amplificare to expand or enlarge. The vacuum tube is the only simplifying device for 40 years and dominated electronics up to When the first BJT was in the market it has created another revolution in the electronics and it is a first portable electronic device like transistor radio developed in the year

Best headphone amplifiers 2021: budget and premium

May 5, ,A. May 5, A. Faulkner, Chicago, Ill. More specifically yet the invention concerns itself with the use of amplifiers in conjunction with such instrumentalities. In accordance with one of its aspects it is a broad object of the invention to provide a novel telephone instrument of the subset or headset type which has improved receiving efficiency and is, therefore, suited for use by the hard-of-hearing.

Electrical Engineering (ELG)

The new device TP allows using the ordinary phones for an audio broadcast of messages and announcements through public address PA or emergency announcement systems. Telephone customer can select zones of broadcast by himself at that. Today, PA communication is everywhere: in shops, in offices, in schools and hospitals, at work areas and warehouses. It is effective in working process settings or for calling a staff from a territory of object. A function of paging is very useful, when a big number of users should have an access to PA system, or when a location of users can be changeable. In such a case, in addition to the remote microphone stations, all telephone sets of local PBX, installed on the object, can be applied for PA broadcast of messages. External urban telephone networks connected directly to TP can also be exploited for paging, unless local PBX is deployed.

Telephones at Home

In mobile phone systems, the 4th generation is widely prevailing in , and in , it is expected that the 5th generation 5G will start to prevail. In both generations, a linear power amplifier PA is used. In case of 4G, in addition, such as the envelope tracking ET and the digital predistortion DPD systems are applied to improve efficiency and linearity. In case of 5G, because of wider modulation band width and parallel operation under the multiple-input and multiple output MIMO mode, it might be difficult to apply all systems as those of 4G.

Headsets 101: Ultimate Guide to Understanding Headsets

RELATED VIDEO: MOSFET Common-Source Amplifier

Headsets have become commonplace in our new iWorld of technology. With so many choices, applications, plug-ins, adapters and options…where do you begin? Our HEADSETS Guide will explain headsets in detail with numerous pictures to help you visualize which devices and cables you need, where and how they connect, along with anything else you need for the perfect headset solution. We will be updating the guide often as technology changes in our complex world of headsets for your office, home, mobile, and computer. Click on the choice below which best describes your headset need:. With hundreds of telephones available on the market, you will find three typical methods used to plug a headset into a telephone: 1 Many older phones and more basic phones will require an amplifier that plugs into the handset port on your telephone.

QSC in Action

The frequency distribution of energy in speech has been determined for six speakers, four men and two women, for a syllable sentence of connected speech, and also for a list of 50 disconnected syllables. The speech was received by a condenser transmitter whose voltage output, amplified 3, fold, was impressed on the grids of twin single stage amplifiers. The unmodified output of one of these amplifiers was measured by a thermocouple and was a known function of the total energy received by the transmitter, corrections being made for the slight variation with frequency of the response of the circuit. The output of the other amplifier was limited by a series resonant circuit to a narrow band of frequencies, the energy in this band being measured by a second thermocouple. The damping of the resonant circuit was so chosen that sufficient resolving power and sufficient energy-sensitiveness were obtained over the range from 75 to 5, cycles per second; and 23 frequency settings were made to cover this range. For each syllable simultaneous readings were recorded on the two thermocouples at each frequency setting. The consecutive syllables were pronounced deliberately by each speaker, maintaining as nearly as possible the normal modulation of the voice.

US2885483A - Telephone instrument utilizing transistor amplifier - Google Patents

There are several advantages with multistage amplifiers, notably achieving high gain with good frequency response and low level distortion. The amplifier we are going to design is a simple cascade connection where four identical stages are connected by RC coupling. In other words we are connecting each stage by using a capacitor in series between the output of the previous stage with the input of the next one.