20
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Why would a digipot require the voltages on its terminals to be between ground and VCC?
This device is far more than "just a resistor ladder". It includes a great deal of digital logic that controls the serial interface and allows you to program the resistance.
The resistors are ...
- 31.7k
6
votes
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Implementing a programmable variable resistor
A series combination of power-of-two resistors will accomplish what you want, though with n resistor values of n resistors for n bits.
So 20 resistor values will give you from 1 ohm to 1.048575 ...
6
votes
Precision Adjustable Voltage Reference
The 5ppm is only a typical spec, and there is no guaranteed maximum. Also the 35ppm is a typical spec (of total resistance drift). Note that the 3-sigma element resistance drift over lifetime is in ...
5
votes
Accepted
100s of devices on SPI bus with daisy chaining - theoretically possible but who's done it?
I think you're good to go. A few points I noticed tho'...
your SDO requires a pullup. So clock speed needs adjustment accordingly (see datasheet)
the 'mega SDO will be driving 8x chips, but I think ...
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5
votes
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How would a fast moving slider of a potentiometer affect reading?
There may be "bouncing" if it's very fast. There will be CRV (contact resistance variation) and some voltage noise as well. CRV affects the reading if the wiper output is loaded, and has ...
5
votes
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Resistor chain substitute
How about this idea?
simulate this circuit – Schematic created using CircuitLab
Choose some suitable MOSFET and, as long as CI is always positive relative to CI return, it'll work. If CI can go ...
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5
votes
Resistor chain substitute
One option to cut down on the number of switches and resistors would be to use a binary chain like this:
simulate this circuit – Schematic created using CircuitLab
Start with all switches ...
- 27.9k
5
votes
Trying to understand (and mimic) the multimeter's interference with a circuit
The pedal cord has 2 wires that connect it to the sewing machine. I analyzed the foot pedal by measuring its resistance (stand-alone, while not connected to the machine) and observed that the ...
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5
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How to control digital potentiometer MCP41010 using ESP32? (running into a weird error)
GPIO35 is input only. Choose a different GPIO for your CS.
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4
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Weird waveform when using potentiometer as volumecontrol
Here's one potential reason:
You're sending an audio signal with a +12 V DC offset into an IC that is designed for much lower voltages.
EDIT: Here is brhans' solution:
simulate this circuit – ...
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4
votes
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Component / Circuit for variable resistance (0, 5K, 100K) at 110V and 1.5Amps @ 0Ohm
A couple of SPST relays will do what you want:
simulate this circuit – Schematic created using CircuitLab
By default (no relays activated), the 100k protection resistor is in the circuit.
...
- 178k
4
votes
Analog voltage control via Microcontroller
If your microcontroller does not have a DAC, you can generate high-frequency pwm, run it through a low pass filter and it is effectively an analog voltage.
Unfortunately if you're trying to get up ...
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4
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X9C103 10k digital potentiometer with LM317 0 - 20 V DC voltage source
Maximum voltage on the digital pot resistive elements is +5V, as specified in the X9C103 datasheet.
There are other digital pots which can deal with higher voltages, but also keep in mind the minimum ...
4
votes
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Need an isolated controllable resistance of about 10 to 20K ohm
You could use a mechanical relay or opto-MOS SSR to switch a resistor in parallel with the existing sensor. Here is an example of a normally-closed opto-MOS relay, so passing current through the LED ...
3
votes
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Software SPI implementation for AVR
As @alex.forencich suggested, I have also tried setting CS to LOW for the whole duration of the data transferring process (for ...
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votes
How can I make a digital audio panning controlled by a microcontroller?
How can I make a digital audio panning controlled by a
microcontroller?
Try using this circuit: -
But scale up the resistors to suit your pot. The down side of using a digital pot is the wiper ...
- 473k
3
votes
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MCP45HV51 Register does not change
I don't understand, why the poti reacts but the register does not change its value. Can anybody help me with that?
The reason is that although the I2C Write commands to the MCP45HVX1 family are ...
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3
votes
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How does a digital potentiometer work?
Second option is a good representation. You can fabricate well matched resistors in CMOS processes, and also well matched analog switches. As ever, the absolute value tolerance for passives in CMOS is ...
- 7,999
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Is it possible to use a digital potentiometer as a digital rheostat?
The MAX5483 and MAX5484 appear to be, the MAX5481 does not appear to be:
Source: MAX5481 datasheet
It appears the MCP4151 can be used as a rheostat:
Source: MCP4131 Datahsheet
Note 1 reads as ...
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3
votes
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Safety circuit to control maximum voltage
If you already have the microcontroller, then a PWM output with an R-C lowpass filter will be more than suitable as a reference voltage source.
But a simple potentiometer and a comparator - or two ...
3
votes
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Do I need to worry about current when using a potentiometer?
The power rating determines the maximum current that can be run through the resistance track. If we take your 1 kΩ, 0.25 W pot as an example we can calculate from \$ P = I^2R \$ the max current as
$$ ...
- 181k
3
votes
Control timing of Monostable Multivibrator
To control the time of a monostable, the resistor (R_x1) should be replaced with a current source that your microcontroller
can adjust. The easiest way to do this, is with an analog output from the ...
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3
votes
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Control timing of Monostable Multivibrator
My first thought was to use a digital potentiometer, such as the AD5141, to replace the Rx1 and Rx2 resistors. They are usually programmed from an MCU via I2C or SPI. The AD1541 does either, offers ...
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3
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AD8400 Digipot: Non linearity in output resistance in rheostat mode
There's no way to have images in comments, nor to have more extensive comments needed to guide you with what's expected of a question, so I'll have to use a part of this answer instead.
The schematic ...
2
votes
How can I make a digital audio panning controlled by a microcontroller?
Since you say the audio is already in digital form, do the gain adjustments digitally. For each incoming sample, multiply it by (1-PAN) to the first speaker and PAN to the second. PAN is a variable ...
- 315k
2
votes
Question about Digital Potentiometers
The "absolute maximum ratings" table in the datasheet is the place to look. It indicates that Va, Vb, and Vw must all remain between 0V and Vdd. Since Vdd cannot exceed 8V, this chip will not work for ...
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2
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Problem with digital potentiometer [MCP41010] in Op-amp Amplifier
The digital pot can have significant capacitance from its analogue pins to both ground and the internal digital clocking input. This means two things: -
high frequency gain is high and op amp noise ...
- 473k
2
votes
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Electronically programmable buck converter module
Andy is right about parasitic capacitances.
Changing feedback resistor values will also change stability conditions. The current source solution is nice, but a simple voltage source connected to the ...
- 82k
2
votes
Electronically programmable buck converter module
On the face of it, it might work but also, because of parasitic capacitances in the digipot, it might turn the regulator into an oscillator or it might produce a much degraded load transient response.
...
- 473k
2
votes
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Using a digital potentiometer in a voltage divider
You need to configure your digital potentiometer as a rheostat. If you connect the wiper with one of the terminals A or B, you will get a variable resistor between the two terminals A and B.
...
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