Logging the Linear Digital Potentiometer - Application Note - Maxim Logging the Linear Digital Potentiometer - Application Note - Maxim

Logarithmic potentiometer simulation dating, your answer

Electronics Basics – How a Potentiometer Works

The taper is the relationship between the position and the resistance of the potentiometer. See the figure below: On panel potentiometers, the wiper is usually the center terminal of three.

Applications[ edit ] Potentiometers are rarely used to directly control significant amounts of power more than a watt or so. To halve the volume again, we would want just 0.

Logarithmic potentiometers

But this is what we want. We don't want the loudness to increase by a fixed amount each step, we want the relative loudness to increase by a fixed amount each step. The 'log pot' is used as the volume control in audio amplifierswhere it is also called an "audio taper pot", because the amplitude response of the human ear is also logarithmic.

Logarithmic potentiometers Non-linear tapers are specially used in audio control applications, namely logarithmic tapers there are also inverse-logarithmic tapers.

Hello hook up 2 shows that the gain of the circuit can be expressed as a function of the wiper setting as a percentage of the potentiometer's full scale setting.

Rheostat To use the potentiometer as a rheostat, only two pins are used: Original Circuit Because the schematic is no longer present in the article, I need to regenerate it. A motor-driven potentiometer may be used as a function generatorusing a non-linear resistance card to supply approximations to trigonometric functions.

Modeling Potentiometers and Variable Resistors

Huge range of input types. Nonlinear Solution for the Modified Potentiometer Circuit. Any three-terminal potentiometer can be used as a two-terminal variable resistor by not connecting to logarithmic potentiometer simulation dating third terminal.

I'll repeat my previous comment, since clearly you glossed over it: One click at the bottom is a change of 1 loudness unit. This creates an output which rises slowly at first due to a high resistance track, then about half way along, the track changes to low resistance, giving a fast rising output from the slider.

Conclusion This is a simple circuit that does what I need, which is to accurately render the exponential function over a limited range. Voltage divider Potentiometers can be used as voltage dividers. Digital potentiometer A digital potentiometer logarithmic potentiometer simulation dating an electronic component that mimics the functions of analog potentiometers.

This guarantees that whatever signal you've got to measure, you can do it with the Sentry. Two Types of Track Two types of potentiometers with different tracks are available.

Budak meant that the plus and minus inputs are at the same voltage i. The 'log pot' is used as the volume control in audio power amplifierswhere it is also called an "audio taper pot", because the amplitude response of the human ear is approximately logarithmic.

Edges of the resistive layer have conductive contacts. Linear-potentiometer tap points are located at equal resistor segments along the entire resistor string.

After initialization and start-up, the circuit produces fast, slow, OK, and error indications. This results in a device where output voltage is a logarithmic function of the mechanical angle of the potentiometer. A disadvantage is that sufficient force must be applied to make contact.

That is, where the center tap is set.

Logarithmic potentiometers

Power is related to voltage according to Ohm's law. Capacitive sensors require no calibration or contact force, only proximity of a finger or other conductive object. If there were ten marks, evenly spaced, we'd have something like: This produces a durable track with stable electrical resistance throughout its working life.

Preset potentiometers are widely used throughout electronics wherever adjustments must be made during manufacturing or servicing. But I get the general impression from reading any of these answers that the logarithmic resistance inverts the biological response, and then look closer at the math described and realize that isn't true.

Television Potentiometers were formerly used to control picture brightness, contrast, and color response.

Schematic for a Circuit with Logarithmic Voltage Output. Basically, the voltage divider is used to turn a large voltage into a smaller one. There is also an anti-log pot or reverse audio taper which is simply the reverse of a logarithmic potentiometer.

Linear vs. Audio

In a linear slider potentiometer, a sliding control is provided instead of a dial control. The service life of these types of potentiometers is typically 1 million to 20 million cycles depending on the materials used during manufacturing and the actuation method; contact and contactless magnetic methods are available.

The Log10 function is used for relative dB scales, so applying the logarithmic function to Ohm's law, simplifying, and aling by ten for significant figures yelds: Each step changes the power by 1dB; turning the control CW 1 step increases the power by a factor of 1.

A fixed resistor having a value about a quarter of the potentiometer value is connected from the low ground end of the potentiometer to the slider. Assume the potentiometer volume control varies the signal power applied to the loudspeaker and assume the amplifier can produce a maximum of W.

The tracks are made by screen printing the paste onto a paper based phenolic substrate and then curing it in an oven. The adjustment can also be completed with either a flat head or "Phillips " screw driver, adding another layer of ease for the user.

One of the advantages of the potential divider compared to a variable resistor in series with the source is that, while variable resistors have a maximum resistance where some current will always flow, dividers are able to vary the output voltage from maximum VS to ground zero volts as the wiper moves from one end of the potentiometer to the other.

There are two main functional types: All logarithmic amplifiers must therefore specify a signal range over which they will "log". In some designs, a simple, low-cost linear potentiometer can be used in place of a logarithmic-taper potentiometer log pot.

When the potentiometer is used as a voltage divider, the wiper position determines the output voltage. Simulation result for Time-varying potentiometer circuit The simulation results show the change in resistance as a function of time versus the output voltage to be measured.

However, they are subject to degradation of performance, or even failure, due to wear and contamination. The classic log amp discussed in most introductory texts exploits the I-V characteristics of a diode The potentiometer can be used as a voltage divider to obtain a manually adjustable output voltage at the slider wiper from a fixed input voltage applied across the two ends of the potentiometer.


A is an arbitrary constant. To use the potentiometer as a voltage divider, all the three pins are connected. Through digital input signals, the resistance between two terminals can be adjusted, just as in an analog potentiometer.

Analysis of My Modified Circuit. That is, it does not change with time.