An ADC is an Analog to Digital Converter. This device converts analog signals into digital form. It is mainly used by the digital circuitry to take analog measurements.
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Why are digital oscilloscopes still so expensive?
I'm a beginner in hobby electronics and I am wondering
why digital oscilloscopes are still so expensive?
In times of cheap GHz CPUs, USB 3, ADSL modems, DVB-S receivers, blu-ray players which all of ...
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5answers
6k views
How do I measure a negative voltage with a ADC?
I am working with a PIC micro-controller with inbuilt 10bit ADC and want to measure a voltage in the range of -1 to -3Volts.
I thought of using an op-amp in the inverting mode to make voltage positive ...
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4answers
461 views
What is a one-bit ADC good for?
I have recently heard of the concept of a one-bit ADC, and have seen it implemented in the context of a sort of digital-to-analog converter (oddly enough), and I'm wondering, what is the point? Why ...
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4answers
522 views
Receive several fm-radio stations at the same time (~10-20 MHz wide summary at 90MHz radiofrequency)
What is a cheap way to receive and record on PC several (tens) of fm-radios (public, e.g. news, music, etc)? Such radios uses frequencies like 90.4 MHz or 102.7 MHz, sends a stereo (sometimes with ...
10
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2answers
468 views
Mixed signal PCB layout for PSoC
I am developing a PCB for an analogue sensing application. It uses the internal ADC on a PSoC3. As usual, the application is very space constrained (11mm x 21mm), so I have had to make some ...
10
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2answers
394 views
How do ADCs fail?
I'm responsible for maintaining a satellite that has an ADC that is failing in an unusual manner. Essentially what is happening is that it toggles back and forth between two values, if the raw voltage ...
9
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4answers
519 views
Effective number of bits of 14-bit ADC
I have a 14-bit ADC. However, looking at the datasheet (see table 2 on page 5), the effective number of bits (ENOB) is always less than 12 bits.
Why is my the DAC claiming to be a 14-bit ADC when it ...
9
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2answers
346 views
How could I power an IC over the Ethernet?
I was looking foward to powering a small Integrated Circuit using only the power provided by the ethernet outlet of my room. Is that even possible?
I've googled and I've found that the voltage that ...
8
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5answers
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ADC input impedance on MCUs
What is the input impedance of a typical MCU ADC? In this case I'm working with a PIC24FJ64GA004. I don't need high speed sampling - a maximum of 100 samples per second.
I wish to connect a resistive ...
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What is a differential ADC?
How does a differential analog to digital converter differ from a regular ADC?
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1answer
294 views
AVR 1.1V Internal ADC Reference Over-Voltage
If I use the internal 1.1V reference for the ADC, and my Analog input exceeds 1.1V, lets say 2.5V, is that harmful to my microcontroller? Or will ADC value simply clip (to 0x3FF) at 1.1V?
For ...
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How to read high voltages on microcontroller?
I want to read high voltages, like ~50V, using a microcontroller. I plan to put this as an input into the microcontroller's A/D line. But of course, you shouldn't have voltage that high on the input ...
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762 views
Recommend any ADC ICs?
I am looking for an ADC IC and while I could just take the plunge and pick one, I was wondering if anyone had any experience with any particular devices? I need it to:
Connect to an AVR via I2C/SPI ...
7
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5answers
1k views
Cascading ADC's to get higher resolution
Suppose I have a pair of 12-bit ADC's, I can imagine that they can be cascaded to get <= 24-bit output.
I can think of simply using one for the positive range and the other for the negative range, ...
7
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2answers
364 views
Selecting bias resistor for thermistor
Rt is thermistor. Rb is bias resistor, which value I need to calculate. The temperature that I'm interested in is giving ...
7
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3answers
914 views
Auto-Ranging Meter Design
I'm designing an auto-ranging voltmeter using the on-board ADC of my micro for A to D and a digital potentiometer as a programmable resistive divider to control the range.
My concern is the ...
7
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2answers
466 views
Grounding of ADC grounds
Fast, high resolution ADCs, especially ones that have parallel output, usually have a separate supply pin (DRVDD, (drive vdd) or OVDD (output vdd)) presumably because they don't want to couple noise ...
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How do I sample a -2 V to +2 V analog signal with a PIC microcontroller?
I am using a PIC micro with a 10bit ADC to take readings from an analog signal with a frequency less than 300 hz. However that analog signal is in the range of -2 V and +2 V. How can I condition the ...
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2answers
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Voltage dividers and ADC's
I want to read a voltage from 0-30V with an MCU ADC which has a maximum input of 3V.
Initially I thought of using a 100k-10k divider (so 33V translates to 3V) but according to the answers to ADC ...
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2answers
442 views
Arduino has an input value in disconnected pin
I'm new to arduino. Maybe is an elemental question...
If I load this program:
...
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3answers
3k views
How to Convert 0 to 10V analog signal to 0 to 2.5V for ADC input?
I have an analog signal which ranges between 0V and 10V. I want to linearly scale it down to 0 to 2.5V for my ADC.
I'm concerned that using a resistive voltage divider will affect signal quality. ...
6
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4answers
535 views
Sensing DC motor current
I am allowing the current through a DC motor to flow through a small resistor and measuring the voltage across it. I need to give this analog Voltage to an ADC of micro-controller to do some signal ...
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3answers
250 views
How to sample and hold on very narrow pulse?
I am looking to construct a simple data logger to record the peak intensity from a flash strobe. When a flash is detected, the peak will be captured (ADC), time stamped and written to memory. The ...
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3answers
834 views
How to Implement an Analog Ground Plane
I have seen this picture in a number of the Atmel datasheets. This one is from the ATTiny48/88 datasheet.
Can someone explain in some detail how to properly implement this on a 2-layer board? I ...
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2answers
752 views
Bluetooth simple oscilloscope
I was thinking to make a simple oscilloscope which can measure at least 2MHz signals, that would be enough, and it will be connected to a PC, or Android device.
First, I tought to use USB to connect ...
6
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4answers
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STM32 ADC Noise 2
I have just tested my second design with STM32F2, now it is STM32F207ZFT6, the ADC behaviour is the same as in my first application - strong noise in ADC.
Noise of current input without any ...
6
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1answer
246 views
Adjusting offset (and possibly gain) of ADC preamp OPAMP with DAC
I am designing simple 200MHz scope for use with FPGA board and came up to idea of software adjustable offset and gain of input preamplifier.
It is using TI ADC08200 and since I am not much ...
6
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1answer
255 views
Is connecting the V_REF- pin for a dsPIC mandatory?
While trying to get the ADC of the dsPICF3013 working (I am getting only zeros back), I have studied the datasheet and the (I will call it) ADC reference for the dsPIC30F family. Previously I only ...
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2answers
619 views
What MCU, need hi res ADCs?
I'm trying to find a powerful MCU that has multiple analogue to digital converters. I want around a 14 bit resolution to do some serious audio sampling.
Any suggestions or comments would be great, ...
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3answers
262 views
Obtaining a -3.3v with +3.3v and ground
I have a +3.3V supply and ground through usb on a board. I want to get a -3.3v supply from it for giving reference to an adc. Do you know how to do it?
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2answers
764 views
Using Pullup and Pulldown Resistors
I've been researching pullup and pulldown resistors after seeing them used in many digital circuits and while I understand what their purpose is, I haven't found any resource on how to determine the ...
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3answers
7k views
How to make a clean amplified microphone analog to digital conversion?
I've asked a couple of questions relating to this project the past couple of days, but I cant seem to put it all together.
I hooked up an electret mic into an opamp and gave output to my arduino ...
5
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1answer
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Measuring light levels with a photodiode and an ADC
I'm trying to use a photodiode to measure light levels via an ADC on an ATMega168. I've got the microcontroller code working properly (measuring values on a pin and reporting it as an led brightness) ...
5
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2answers
680 views
ADC data.. Is something fishy?
Folks,
I have been playing with STM32F2 (probably the most advanced ARM Cortex M3 in the market). This is not a processor specific question nonetheless.
I have a set up where I have 0V sampled by ...
5
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4answers
1k views
High Quality Audio ADC and DAC with Embedded
I am starting work on a project where I want to do some DSP using an embedded solution ideally with very low latency as it will be in a real time environment. In addition I want high quality, ...
5
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3answers
554 views
Instrumentation Amplifier - how to use it correctly
I am trying to perform some measurements based on a special technique used to detect corrosion in rebars of concrete bloc. The idea is to measure the potential difference between an electrode and the ...
5
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2answers
621 views
How to ground a floating ADC input
I have an ADC input that may be connected to an external sensor (based on how the user configures it). If I leave the input floating, I get a wide range of ADC values.
Is there a way to weakly ...
5
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4answers
164 views
Quantization noise and Quantization error
What is the difference between the quantization noise and quantization error in ADC?
I understood that the quantization error you get when you convert analog to digital and quantization noise when ...
5
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3answers
594 views
Measuring Resistance of a Wire With an ADC
I'm trying to design a circuit which can measure small resistances down to 0.1 Ohm and a max. of 10 Ohms. I won't be measuring actual resistors but rather large coil of wires, upto 500 m (as you can ...
5
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4answers
403 views
Current sensing power supply for hobby servos
I'm trying to design a power supply for 8 hobby servos which senses the current consumed by each of them. Size and cost are the main drivers, much more so than absolute accuracy.
I'm designing for 1A ...
5
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1answer
297 views
Protection of ADC inputs
I am using an ADC MCP3424.
After breaking one of the ADC inputs, I was saw this thread:
ADC input protection?
I also read Microchip app note TB3013. Figure 3 in particular:
The ADC's analog ...
5
votes
2answers
329 views
Peak detector (peak event)
I have a problem which is somehow related to detecting a peak. Let me summarize the problem a little bit, so it might be clear to you. I have to signals, both are not periodic and I know when they ...
5
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2answers
1k views
What is the purpose of ADC sampling time?
I am trying to understand the usage of ADC sampling time?
The ADC I have has a programmable sampling time of 100nsec/500nsec and 1uSec. What is the primary use case of longer sampling time, why ...
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4answers
206 views
Tiny 8MSPS DSPs?
I have a problem: I've got five tiny CMOS image sensors (2mm x 2mm), each in a small space (about 10mm x 15mm). They take a clock signal in, and output an analog signal, requiring an 8MSPS ADC each. ...
5
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1answer
292 views
When to use buffer/ low-pass filter on ADC input?
Sorry if this is a bit of a sophomoric question, but when should you buffer an ADC input, specifically from a potentiometer. I've seen circuits add a low-pass to the wiper/ ADC input.. is this only ...
5
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1answer
130 views
A/D Beginner Question
I want to just get an idea about the complexity of a hobby project before getting started on it.
I want to use a sensor that outputs an analog voltage. However, I want to use an A/D convertor to ...
5
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1answer
412 views
What does “limit cycle” mean in delta-sigma modulator?
Could anyone explain limit cycle related spurious tones? It is stated that a higher order modulator is better than low level one because of limit cycle related spurious tones, but I don't have picture ...
5
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1answer
156 views
AVR Pin Dual Use: Input and Output at (seemingly) the same time
I have been working on a few different versions of a bicycle light control circuit which reads in various buttons and sets various outputs accordingly such as headlight, taillight, blinkers, etc.
My ...
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3answers
921 views
msp430 ADC overvoltage
The maximum input voltage of a msp430 is Vcc+0.3V. What is the result of the ADC if I provide Vcc+0.3V as input? Is the digital output of the ADC just the maximal value?
Thanks
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3answers
649 views
Increasing ADC resolution by supersampling on a successive approximation ADC
Is it possible to increase the resolution of an ADC by supersampling on a PIC24F ADC, which has 10 bits of resolution and is implemented using a successive approximation engine? Speed is not critical ...
