• maverick99
In summary: This is why in schematics, or on circuit diagrams, a resistor's value is usually given in terms of ohms (Ω), with the 'k' suffix meaning 'megaohm' or 1,000,000 ohms. When adjusting a variable resistor, you want to find the value that gives you the 'diode on' indication on the circuit diagram. You can do this by trial and error, or by using a voltmeter and measuring the diode voltage across the resistor when the current is set to the value that gives the desired 'diode on' indication. To adjust VR1 (the variable resistor), turn it until the diode voltage across it matches the voltage required for the
maverick99
I'm building a circuit in one of my classes and it asks for a variable resistor. On the schematic it's value is 47kohms. On the circuit diagram I'm building this from, it says to adjust VR1 (variable resistor) until a diode comes on. First off, what exactly is a variable resistor? Second, how do i adjust it??

It's like a typical resistor but you can adjust its resistance yourself. You need to find youself a variable resistor marked with 47kohms which means its resistance can be adjusted between 0and 47kohms.

See below for further details:

http://www.kpsec.freeuk.com/components/vres.htm

well crap i didn't know they were the same things as pots. Thanks

u find various kinds of pot with different ressitance. pick any one, supply a constant current of some amperes and connect a volt meter parallel to the pot, with the current supplied and adjust the pot with the reading on the volt meter so u get the result of the resistance required with the formula V/ i = R

maverick99 said:
well crap i didn't know they were the same things as pots. Thanks
Very often a 'variable resistor' in a circuit is a 'pot' (linear potentiometer), simply a carbon strip with a sweeping contact. In low voltage, low current applications this is usually the case, such as in audio mixers, or stereo tone controls.

However, (not always obvious from the circuit diagram), sometimes a wire-wound resistor is required with a screw-down or soldered set of taps. Most linear pots cannot handle any serious kind of voltage or amperage without frying or arcing. Even in seemingly 'low' voltages in the range of say 120 VAC house currents (dimmer switches) or low current situations like guitar amp balance circuits for high voltage output stages, ordinary pots will simply present a fire-hazard and danger to other components.

You need to be sure of voltages and currents to know if a 'pot' is a safe application.

Secondly, because most high power resistors have to be wire-wound copper coils with sweeps, they have frequency-response side-effects that have to be taken into consideration. That is, they will have an impedance as well as a resistance, which affects both frequency response and phase of voltages and currents in the circuit.

## 1. What is a variable resistor?

A variable resistor is an electronic component that can be adjusted to change the amount of resistance in a circuit. It is used to regulate the flow of electric current and can be adjusted to control the output of a circuit.

## 2. How does a variable resistor work?

A variable resistor works by changing the length of the resistive material in the circuit. This changes the amount of resistance that the current has to overcome, altering the flow of electricity through the circuit.

## 3. What are the different types of variable resistors?

There are several types of variable resistors, including potentiometers, rheostats, and trimmers. Potentiometers have a rotating knob or slider to adjust resistance, while rheostats have a rotating shaft. Trimmers are small variable resistors that are used for fine-tuning in electronic circuits.

## 4. What are some common uses for variable resistors?

Variable resistors are commonly used in electronic circuits to adjust the intensity of a signal, control the volume in audio devices, and regulate the speed of electric motors. They are also used in scientific experiments to measure the resistance of different materials.

## 5. How do you choose the right variable resistor for a circuit?

The right variable resistor for a circuit depends on the specific needs of the circuit. Factors to consider include the required range of resistance, power rating, and physical size. It is also important to choose a variable resistor with a suitable tolerance level to ensure accurate resistance values. Consulting a datasheet or seeking professional advice can help in selecting the right variable resistor for a circuit.

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