Questions tagged [r2r]

An R-2R Ladder is a simple and inexpensive way to perform digital-to-analog conversion, using repetitive arrangements of precision resistor networks in a ladder-like configuration.

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R-2R ladder connected to amplifier causes voltage to DECREASE

I'm working on a project and requires 4-bits of data from a micro-controller. I chose R to equal 1k ohms and the max V_out from the DAC (V_R-2R) without the amplifier measures around 1.6V and the ...
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2answers
1k views

Why is my basic DAC incorrect?

I tried to make a basic R2R digital to analog converter in a simulator. Even with all bits set, I get an output of 4.98V rather than the 5V I would expect. I expected 5V since so many online resources ...
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0answers
50 views

Any alternative to relay?

I am working on Project which is to make a PID based line follower but the constraints are 1.5 IR Sensors are allowed 2.only 9V battery 3.No Micro controller only discrete components I though of ...
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2answers
185 views

16 bit R2R DAC?

I want to build a 16 bit R2R DAC using two 74HC595 chip. I need the DAC to replace the potentiometer of a lab PSU. While researching, in the forums and basically everywhere they suggested that R2R ...
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2answers
1k views

Is this how a R-2R DAC for VGA should work?

I'm trying to wrap my head around if this is how a R-2R DAC should work. I say should for two reasons: (1) because I think I understand the theory behind the resistor ladder of subsequent voltage-...
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5answers
5k views

Why can't this LM324 op amp reproduce a signal above a certain frequency?

There seems to be no shortage of circuits like this that attempt to use an R2R as a DAC and an op. amp. as an output buffer. These make sense to me so I decided to try and construct one. I ...
7
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1answer
933 views

How Significant is VGA Impedance Matching?

I've seen a multitude of different resistor DAC solutions for a VGA signal, however they almost always have an impedance of >200 ohms per color, e.g. when I've been lead to believe that we want to ...
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1answer
80 views

converting digital signals to analog

I'm trying to take 12 digital signals and convert them to a linear analog signal (0-10 V or 0-20 mA). In an ideal world each digital signal would increase the analog output by 0.83 V and it wouldn't ...
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0answers
66 views

Precision battery voltage meter, Auto adjustment by R-2R

For a more precise measurement of a battery voltage I'd like to apply auto adjustment. The input voltage ranges from 2.5V-4.2V (single cell) to 20V-72V (module). At the moment the input voltage is ...
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0answers
158 views

What could cause a gain error in the R-2R DAC?

I was studying R-2R ladders and I still what causes a gain error in the R-2R. I assume that it could be caused by an error in the R or 2R resistors. I don't think that a mismatch in the feedback ...
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2answers
457 views

R-2R Ladder Resistors Mismatch

I am still trying to understand what kind of errors are caused in the R2R ladder depending on the amount of resistor mismatch relative to the others. For example if you have a mismatch of 12% in the ...
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1answer
311 views

How do you output whole number voltages (1-4V) from an Arduino/5V source using only digital pins and passive components?

I would like to output whole number voltages 0V,1V,2V,3V and 4V from two digital pins on an arduino/5V source. A simple r2r ladder doesn't seem like it would work because it would split its definition ...
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1answer
344 views

Please review my schematic design

This is my first design, a 4-Bit stereo DAC with LM386 amplifier. I'm using it to interface with my FPGA eval board which doesn't have any audio connector. My board uses a 2x6 'PMOD' connector. My ...
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2answers
539 views

Add a voltage offset to a resistor ladder R-2R

I want a cheap DAC from a microcontroller for audio output. A resistor ladder is one solution. The output needs to be buffered by an op amp. Most op amps have some limitation on how close the input ...
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3answers
3k views

Output impedance of the current output DAC

As known there are two types DAC using R-2R ladder. One is voltage output and another is current output. The voltage output type has a constant output impedance which equal to R. The current output ...
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2answers
2k views

Reason for brief spike in op amp output when crossing 0V?

Does anyone recognize this spike in the output of an op amp when the signal crosses 0V? It spikes up when crossing up and down when crossing down. In one of the EEVBlog videos, Dave pointed to ...
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2answers
811 views

R-2R ladder D/A converter with mutilple non-zero inputs

PROBLEM: So I am not used to r-2r ladders where 3 out of 4 inputs are 0V. Here both A and B are 5V, so I don't know how to approach this problem. This is what i get when i simplify the ladder: I ...
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1answer
507 views

R2R DAC in reverse

Knowing how voltage dividers work, this probably isn't possible. But, is there a way to run an audio signal back through an R2R arrangement and get 8bit digital signals back out without complex ...
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2answers
1k views

Signal generator: PWM or R2R?

I want to build a signal generator using a ATmega 328P on an Arduino. Which way would be better. Using one of the timers (8bit or 16bit) built in to generate a PWM and then low-pass filter it, or ...
2
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2answers
613 views

Converting Pulses to Analog Input for Mic

A continuation of this question. I am attempting to read two flow meters through the mic port of a phone/tablet. The flow meters' pulse pins toggle between +0V and +5V as their pinwheels rotate. I ...
7
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4answers
996 views

Counteracting Sound Card AC Coupling for Reading Digital Data

Disclaimer: I am new to EE. Everything I have learned so far I have taught myself from reading online and posting questions like this while working on this project. I apologize if I do a poor job of ...
3
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1answer
136 views

Reading Flow Meters from Mic Port

I am attempting to read two hall-effect flow meters through the audio-in (mic) port of an Android device. I want to be able to read both flow meters independently. The audio-in port is a standard ...
4
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1answer
1k views

Arduino audio output via R-2R DAC - biasing output for piezo speaker

I followed a tutorial on 8-bic DACs using an R-2R resistor ladder. I am outputting a sine-wave using data from 0 to 255 on pins 0-7. This goes through the pins into the R-2R DAC producing an analogue ...
3
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1answer
633 views

Weird samples from SAR ADC

I am playing around with some SAR (Successive Approximation) A/D-converters. I have made a test circuit where I have a 16-bit DAC from Texas Instruments (R2R-based) and an 16-bit SAR ADC from Analog ...
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1answer
5k views

Can I use ATmega328 TX/RX pins to drive an R2R network and still use the serial port to program the MCU?

Background I wanted to make a simple function generator with an ATmega328 and an R2R resistor network, similar to Jesper Hansen's Mini DDS (Direct Digital Synthesis). To make the function generation ...