adc

100 Articles

Uninvasive EEG Interface Could Be Used To Play Games

August 14, 2026 by 6 Comments

These days, most of us interface with our computing devices in the same old-fashioned ways—via keyboards, mice, and touchscreens. The idea of a more direct brain-to-machine interface remains appealing to many. [Ildar Rakhmatulin] and [Youssef El Abbass] have been working on just such a device, with an eye to using it for gaming.

The device is referred to as Octopus 16, so named because it combines sixteen EEG electrodes into a single compact package, along with the required common reference and ground. The contacts themselves are pogo pins, assembled into a coin-sized cluster. The device is strapped to the head, pushing the contacts against the scalp, and data from the electrodes is then siphoned off to a host machine via Bluetooth Low Energy. The EEG signals are picked up with a pair of Texas Instruments ADS131M08 ADCs, each with 8 channels, with a resolution of 24-bits to capture fine detail in whatever the brain is doing. An ESP32 microcontroller is responsible for grabbing the ADC output and trucking it out over Bluetooth.

The rig is designed for use with the PiEEG software platform. The team have experimented with the device, showing it off by using the EEG signals to detect an individual’s focus state and using that to feed into simple game environments.

Ultimately, what has been shown so far is not so different from the old Force Trainer toy, but the design might prove useful if you’re looking into doing EEG experiments on a budget. Just do your due diligence to make sure you’re getting more signal than noise out of those lovely 24-bit ADCs. Video after the break.

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So Many Analog To Digital Converters

June 11, 2026 by 47 Comments

An old algebra teacher used to say, “You have to take what you know and use it to get what you don’t know.” You might say the same thing about converting analog signals into digital. Computers know how to count and keep time. [Eric Explains] has a video purporting to explain “every type of analog-to-digital converter.” We aren’t sure he got every possible method, but there’s still a lot of information in the video, which you can see below.

From the flash ADC, using a ton of comparators to the successive approximation converter, which essentially plays a game of hi/lo, guessing the answer and figuring out if the real answer is higher or lower.

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How Bad Can A Cheap Knockoff ADS1115 ADC Be?

October 15, 2025 by 29 Comments

Although the saying of caveat emptor rings loudly in the mind of any purveyor of electronic components, the lure of Very Cheap Stuff is almost impossible to resist. Sure, that $0.60 Ti ADS1115 ADC on LCSC feels like it almost has to be a knock-off since the same part on Digikey is $4 a pop, and that’s when you buy a pack of 1,000. Yet what if it’s a really good knockoff that provides similar performance for a fraction of the price, such as with those cheap ADC boards you can get from Amazon? Cue [James Bowman] letting curiosity getting the better of him and ordering a stash of four boards presumably equipped with at least some kind of cheapo knockoff part, mostly on account of getting all boards for a mere $2.97.

The goal was of course to subject these four purported ADS1115s to some testing and comparison with the listed performance in the Ti datasheet. Telling was that each of the ADCs on the boards showed different characteristics, noticeably with the Data Rate. This is supposed to be ±10% of the nominal, so 7.2 – 8.8 times per second in 8 samples per second mode, but three boards lagged at 6.5 – 7 SPS and the fourth did an astounding 300 SPS, which would give you pretty noisy results.

Using a calibrated 2.5 voltage source the accuracy of the measurements were also validated, which showed them to be too low by 12 mV. The good news was that a linear correction on the MCU can correct for this, but it shows that despite these parts being ADS1115 compatible and having features like the PGA working, you’re definitely getting dinged on performance and accuracy.

[James] said that he’s going to run the same tests on an ADS1115 board obtained from Adafruit, which likely will have the genuine part.  We would also love to see someone test the $0.60 version from LCSC to see whether they can match the datasheet. Either way, if you are eyeing this ADC for your own projects, it pays to consider whether the compromises and potential broken-ness of the knockoffs are worth it over coughing up a bit more cash. As they say, caveat emptor.

ASIC physical layout

The Entire Process Of Building An Open Source Analog ASIC

October 8, 2025 by 6 Comments

Our hacker [Pat Deegan] of Psychogenic Technologies shows us the entire process of designing an analog ASIC. An ASIC is of course an Application-Specific Integrated Circuit, which is basically just custom hardware. That’s right, “just” custom hardware.

Services such as those from Tiny Tapeout make it possible to get your hardware designs built. And tools such as those found in Tiny Tapeout Analog Design VM with Skywater 130 PDK make it possible to get your hardware designs… designed.

In the video [Pat] takes you through using xschem (for schematic capture) and magic (for physical layout) to design a custom ADC. We learn that when it comes to hardware you have the choice of many different types of FETs, and not much else. Capacitors are expensive and to be avoided. Inductors are verboten. Getting specific values for things (such as resistors) is pretty much impossible so you generally just have to hope that things come out in relative proportions.

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A High Resolution ADC From Scratch

October 4, 2025 by 6 Comments

It’s a well-known conundrum that while most computers these days are digital in nature, almost nothing in nature is. Most things we encounter in the real world, whether it’s temperature, time, sound, pressure, or any other measurable phenomenon comes to us in analog form. To convert these signals to something understandable by a digital converter we need an analog-to-digital converter or ADC, and [Igor] has built a unique one from scratch called a delta sigma converter.

What separates delta sigma converters apart is their high sampling rate combined with a clever way of averaging the measurements to get a very precise final value. In [Igor]’s version this average is provided by an op-amp that integrates the input signal and a feedback signal, allowing for an extremely precise digital value to be outputted at the end of the conversion process. [Igor] has built this one from scratch as well, and is using it to interface a magnetic rotary encoder to control digital audio playback.

Although he has this set up with specific hardware, he has enough detail in his video (including timing diagrams and explanations of all of the theory behind these circuits) for anyone else to build one of these for other means, and it should be easily adaptable for plenty of uses. There are plenty of different ADC topologies too, and we saw many different ones a few years ago during our op-amp challenge.

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Pi Pico Powers Parts-Bin Audio Interface

June 20, 2025 by 10 Comments

USB audio is great, but what if you needed to use it and had no budget? Well, depending on the contents of your parts bin, you might be able to use [Veyniac]’s Pico-Audio-Interface as a free (and libre! It’s GPL3.0) sound capture device.

In the project’s Reddit thread, [Veyniac] describes needing audio input for his homemade synth, but having no budget. Necessity being the mother of invention, rather than beg borrow or steal a device with a working sound card, he hacked together this lovely device. It shows up as a USB Audio Class 2.0 device so should work with just about anything, and offers 12-bit resolution and 4x oversampling to try and deal with USB noise with its 2-channel, 44.1 kHz sample rate.

Aside from the Pico, all you need is an LM324 op-amp IC and a handful of resistors and capacitors — [Veyniac] estimates about $10 to purchase the whole BOM. He claims that the captured audio sounds okay in his use, but can’t guarantee it will  be for anyone else, noise being the fickle beast that it is. We figure that sounding “Okay” has got to be pretty good, given that you usually get what you pay for — and again, [Veyniac] did build this in a cave with a box of scraps. Well, except for the cave part. Probably.

While the goal here was not to rival a commercial USB sound card, we have seen projects to do that. We’re quite grateful to [Omadeira] for the tip, because this really is a hack. If you, too, want a share of our undying gratitude (which is still worth its weight in gold, despite fluctuations in the spot price of precious metals), send in a tip of your own.

Low Cost Oscilloscope Gets Low Cost Upgrades

April 20, 2025 by 50 Comments

Entry-level oscilloscopes are a great way to get some low-cost instrumentation on a test bench, whether it’s for a garage lab or a schoolroom. But the cheapest ones are often cheap for a reason, and even though they work well for the price they won’t stand up to more advanced equipment. But missing features don’t have to stay missing forever, as it’s possible to augment them to get some of these features. [Tommy’s] project shows you one way to make a silk purse from a sow’s ear, at least as it relates to oscilloscopes.

Most of the problem with these lower-cost tools is their low precision due to fewer bits of analog-digital conversion. They also tend to be quite noisy, further lowering the quality of the oscilloscope. [Tommy] is focusing his efforts on the DSO138-mini, an oscilloscope with a bandwidth of 100 kHz and an effective resolution of 10 bits. The first step is to add an anti-aliasing filter to the input, which is essentially a low-pass filter that removes high frequency components of the signal, which could cause a problem due to the lower resolution of the device. After that, digital post-processing is done on the output, which removes noise caused by the system’s power supply, among other things, and essentially acts as a second low-pass filter.

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