Why are potentiometers used in amplifiers

Add a comment. Active Oldest Votes. In the light of my attempt this makes much more sense. And should the pot be before or after the input capacitor? The pot law should be logarithmic, as our hearing is logarithmic. Use a 10k or k as they are easy values to get, and are high enough so they don't load down your music source. If you have to use a linear pot, read sound. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password.

Post as a guest Name. Email Required, but never shown. The Overflow Blog. Does ES6 make JavaScript frameworks obsolete? Podcast Do polyglots have an edge when it comes to mastering programming Featured on Meta. Now live: A fully responsive profile. An alternative to Ruffle is another browser, Maxthon 4. The following diagram shows how the schematic symbol relates to the drawing of the potentiometer. This is the inside of the potentiometer shown at the top of the page. The back has been removed and placed next to rest of the potentiometer.

The left side shows what the resistive element looks like. It's the wider black area. Below is a close-up photo of the wiper mechanism. The four parallel contacts at the top make contact with the resistive element. The two contacts below those make contact with the inner ring. If you look 'behind' the white insulator, you can see the wiper contacts for the other half of the potentiometer touching the resistive element.

A pot connected as it is in the following diagram will act to divide the voltage like the 2 individual resistors. You can also see that 12 volts is applied to terminals 'A' and 'B' are connected to the 12 volt battery.

In the middle of travel, the resistance from the sliding terminal to either of the other terminals is half of the total resistance. Resistance Taper: In the previous paragraph, I mentioned that the potentiometer had a 'linear' taper. These are general purpose potentiometers and may be used for controlling DC voltage as it did in the diagram or to control the levels of the individual bands on an equalizer. For volume controls you need to use a potentiometer with a 'log' short for logarithmic taper.

If the sound size of the speaker is unchanged, the fault is in the latter stage circuit; otherwise, the fault is in the previous stage circuit. The sound caused by the post-amplifier circuit is light, mainly due to two reasons: insufficient output power and insufficient gain. It is possible to determine which cause is caused by appropriately increasing the input signal for example, adding the signal output from the recorder to the speaker directly to the input of the rear stage power amplifier circuit, changing the volume of the recorder, and observing the change in the output of the power amplifier.

If the input signal is increased, the output sound is large enough, indicating that the power output of the power amplifier is sufficient, but the gain is reduced.

It should be checked whether the contact resistance of the relay contact increases, the input coupling capacitance decreases, and the resistance of the isolation resistor increases. Negative feedback capacitor capacity becomes a smaller or open circuit, negative feedback resistor resistance increases or opens.

If the input signal increases, the output sound will be distorted, and the volume will not increase significantly, which indicates that the output power of the post-amplifier is insufficient.

First, check whether the positive and negative supply voltages of the amplifier are low if only one channel is light, it is not necessary to check the power supply , whether the performance of the power tube or integrated circuit has deteriorated, and whether the resistance of the emitter resistor is increased or not.

The sound caused by the switch and potentiometer in the pre-stage circuit is light and easy to find by visual inspection, which can be cleaned or replaced. If it is suspected that a signal coupling capacitor fails, it can be tested in parallel with the same value capacitor; the performance of the amplifier tube or op-amp integrated circuit is poor, and it can also be checked by the substitution method. In addition, there is a problem with the negative feedback component, which also causes the circuit gain to drop.

The noise of the amplifier is a hum, pop, induced noise and white noise. You should first determine whether the noise is from the previous stage or the latter stage during maintenance. The signal connection plugs of the front and rear stages can be removed. If the noise is significantly smaller, the fault is in the front stage circuit; otherwise, the fault is in the latter stage circuit. AC sound refers to the low-pitched, monotonous and stable Hz AC hum, which is mainly caused by poor filtering of the power supply.

It should be checked whether the power rectifier, filter and voltage regulator components are damaged. The decoupling capacitors at the power supply terminals of the front and rear stage amplifier circuits are either weakly soldered or failed, and a low-frequency oscillation noise similar to the hum is also generated.

Inductive noise is a complex and harsh humming component, mainly due to poor switching of the front-end circuit, poor grounding of the potentiometer, or poor signal wiring shielding. The popping sound refers to the intermittent strange sounds. In the pre-stage circuit, it should be checked whether the signal input plug and the socket, the transfer switch, the potentiometer, etc.

The post-amplifier circuit should check whether the relay contacts are oxidized, whether the input coupling capacitor is leaking or has poor contact. In addition, the soft input breakdown of the differential input tube or constant current tube in the latter stage circuit also produces noise similar to electric spark.

White noise refers to the random continuous "sand" sound, which is usually caused by the poor performance of the input stage transistor, FET, or op-amp integrated circuit in the front and rear stage amplifying circuits. The component of the specification is replaced by a test. The distortion fault is caused by the offset of the working point of a certain amplification stage or the work of the output stage of the power amplifier.

During the inspection, the specific fault location can be judged according to the change of the output power and distortion of the amplifier. If the tube amplifier is distorted and the output power becomes small sound is light , it should be checked whether the aging of an amplifier tube in the push-pull amplifier, the working point is incorrect, or the output transformer is partially short-circuited, causing its work imbalance; if the distortion is at the same time, the output power becomes larger.

Mostly due to the resistance change in the negative feedback circuit, the capacitor failure or the bypass capacitor short circuit of the cathode self-generated bias. If the distortion of the transistor amplifier increases significantly with the increase of the volume, check whether the operating point of a transistor of the pushing stage is offset usually in a power amplifier without a protection circuit or the capacitance distortion in the feedback circuit; If the size is distorted, the fault is in the preamplifier circuit, and the operating point of each amplifier tube should be checked for offset.

Abnormal operation voltage of the integrated circuit amplifier or internal damage of the power amplifier integrated circuit can also cause distortion referring to a machine without a protection circuit. The howling fault is caused by self-excitation in the circuit and is divided into low-frequency howling and high-frequency howling.

Low-frequency whistling refers to the low-frequency "beep" sound, which is usually caused by poor power supply filtering or decoupling usually accompanied by buzzing, whistling. At this time, you should check whether the power supply filter capacitor regulator and decoupling capacitor have failed to open, increasing the internal resistance of the power supply.

If the performance of the power amplifier IC is poor, whistling faults will also occur at low frequencies, and the operating temperature of the integrated circuit will be very high at this time.

The frequency of high-frequency whistling is relatively high, which is usually caused by the failure of the high frequency absorbing capacitor in the amplifying circuit or the deterioration of the performance of the preamplifier integrated circuit.

It can be checked by connecting a small capacitor to both ends of the damping capacitor or decoupling the capacitor of the post-amplifier circuit. In addition, when the negative feedback element is damaged, changed or desoldered, high-frequency positive feedback will also occur and high frequency howling will occur. Some cheap amps are screaming when they are turned on, which not only affects the sound quality but also makes people upset. Here are a few ways to deal with it:.

Some power amplifiers may still have a grounding point even after the above processing, and the grounding point may be imappropriate. Generally, the grounding point should be selected near the filter capacitor, and the "one-point grounding method" should be adopted.

If the static potential of the output stage deviates from the zero points, it will produce a great humming sound. At this time, it may be a zeroing resistance or a problem with the output tube.

The output point potential of the power amplifier can be carefully adjusted, which should be below mv. You should carefully check whether some components of the power amplifier, such as the tube, are damaged at zero point. First, short the input end of the preamplifier to the ground to see if the noise disappears. If the noise disappears, the noise can be determined to be from the input signal line. It can be replaced with a three-core shielded cable.

Note that the shield can only be grounded at one end. In addition, the coupling capacitor should use a small leakage capacitor, such as tantalum capacitor , MKP capacitor, etc. What is the basic principle used in potentiometer? The principle of a potentiometer is that the potential dropped across a segment of a wire of uniform cross-section carrying a constant current is directly proportional to its length. The potentiometer is a simple device used to measure the electrical potentials or compare the e.

What is application of potentiometer? Application of Potentiometer Audio control: Both linear, and rotary potentiometers, are used to control audio equipment for changing the loudness and other audio related signals. Motion control: In order to create a closed-loop control, potentiometers are used as position feedback devices known as a servomechanism. How do you identify potentiometer terminals? The first terminal, or terminal 1, is your ground.

The middle terminal, or terminal 2, is the input signal for the pot. The third terminal, or terminal 3, is your output signal. The shaft on top controls a small ring attached to the second terminal.

Does a potentiometer change voltage? Potentiometers, trimmers, and rheostats are all variable resistors. Potentiometers and trimmers are used to create a variable voltage by varying the voltage between their wiper terminal and two ends. Rheostats are used to vary the amount of current.

How do you wire a LED potentiometer? How is a potentiometer wired? How do you wire an audio potentiometer? Where is potentiometer used? The measuring instrument called a potentiometer is essentially a voltage divider used for measuring electric potential voltage ; the component is an implementation of the same principle, hence its name. Potentiometers are commonly used to control electrical devices such as volume controls on audio equipment.

How do you connect a sound potentiometer? Connect the voltmeter's terminals to the input and output terminals on the pot. Turn the voltmeter on and turn the dial to feed a signal. Turn the knob on top of your pot to adjust the signal. If the signal reading on the voltmeter goes up and down when you turn the knob, your potentiometer works. How do you wire a potentiometer to a speaker? All audio potentiometers are log tapers. Now to connect the potentiometer, this is done by hooking up the positive terminal of the speaker to either one of the two terminals of the potentiometer doesn't matter which and then hooking up the wiper of the potentiometer to the positive terminal of the 3.

Recommended Reading. What is a Digital Potentiometer? Application and Selection. Apogeeweb 27 May IntroductionThe digital potentiometer is mainly used to indicate the furnace temperature of the heat treatment furnace, and automatically controls and automatically records the holding time, temperatu Continue reading ». Potentiometer Circuit: Potentiometer Problems and Repair.

Apogeeweb 6 Dec Warm hints: This article contains about words and the reading time is about 18 mins. IntroductionPotentiometers are widely used and are commonly used electronic components in circuit design. Common Potentiometer Types and Applications Available. Apogeeweb 18 Jun If only two terminals are used, one Apogeeweb 31 Jan