Minimum Viable Arduino Project: Aeropress Timer

https://netninja.com/2025/12/01/minimum-viable-arduino-project-aeropress-timer/

44•surprisetalk•2mo ago

Comments

stephenhandley•2mo ago

This is the first I'm hearing an aeropress 30 second plunge time, what's that about?

jaffa2•2mo ago

Its just how long you are meant to let the coffee brew. Try if you make tea you need to let bag steep for a minute or 2. But actually timing it???? Useful if you are a goldfish may be but otherwise i dont understand who can’t remember to do something in 30 seconds.

Fwiw i oftrn let me aeropress brew for a few minutes. 30 secs is hella short.

pekka22•2mo ago

That’s indeed quite short for a brew time. 30s is your typical plunging time

Tarq0n•2mo ago

30 seconds works fine for other semi-pressurized brewing methods like turboshots or soup.

fabian2k•2mo ago

There are many different ways to use the Aeropress. I'd assume that the recipe the author is following simply asks for a 30 second steep time.

I personally found that the time actually doesn't matter that much, you control extraction by grind size, water temperature and agitation. It might be that if you grind too fine you can still reduce extraction by cutting the time short, but that seems rather inconvenient for this method.

I usually let it steep for 5 minutes, but the exact time doesn't change much. Shorter times aren't that desirable for me anyway as the coffee is still too hot then as I start with boiling water.

thenthenthen•2mo ago

The grind is the most important part I think. Super fine espresso grinds taste the best for me. Coarser, like french press grounds, need a longer agitation/agitation time but still have less taste.

esperent•2mo ago

The idea is that the more pressure you use, the more unwanted materials like fines and oils will get though the paper. So if you press slowly and stop when you hear a hiss, you should have a better brew.

It does make sense, if imagine pressing through in 5 seconds vs 30 seconds, that the paper filtration would work better in the slower press. But I'm not sure if anyone has scientifically measured this.

Actually wait, it's coffee. Someone has definitely scientifically measured it and probably published a two hour YouTube video with their results.

techwizrd•2mo ago

I've had good results from the James Hoffman recipe [0], although I brew inverted. You can push the plunger down with just the weight of resting your arm on the plunger. For something very different, you can brew something not-quite-espresso using the Fellow Prismo cap for the Aeropress.

0: https://www.youtube.com/watch?v=j6VlT_jUVPc

esperent•2mo ago

Personal opinion is that the whole point of aeropress is that you don't need to follow any recipes to get a good result. The parameters are extremely flexible to the point of being close to foolproof. Start with good beans and water. Grind anywhere between French press and very fine pourover level. Brew anytime between 1 minute and 8 minutes. Add anywhere between 100ml and 200ml of water. Press reasonably slowly.

The results will always be good. Maybe not the level you'd get with extremely high quality light roasted beans and a very careful pourover technique, but maybean aeropress isn't the best brewer for those beans in the first place.

SamBam•2mo ago

30 seconds is indeed the _original_ Aeropress recommended brew time. [1] You're supposed to mix the grounds and start plunging nearly immediately, finishing in about 30 seconds. So, indeed, much of the water passes through even before 30 seconds.

That was way too short. It looks like they've finally updated the instructions somewhat, now recommending 60 seconds before starting to plunge. [2]

It works because they also recommend a very fine grind, but that's still pretty short. It looks like Counter Culture recommends using regular pour-over grind and the inverted method and 2-3 minutes, [3] which happens to also be what I do. Though I'm not really particular, so long as it's somewhere between about 1.5 and 3.5 minutes. (Breakfast is a hectic time while also handling kids...)

1. https://www.seattlecoffeegear.com/pages/product-resource/aer...

2. https://aeropress.com/pages/how-to-use

3. https://counterculturecoffee.com/blogs/counter-culture-coffe...

sponno•2mo ago

From James Hoffmann he recommends 2 minutes. If I recall correctly waiting longer did slightly improve the results but after 2 minutes you get a good brew. https://aeroprecipe.com/recipes/james-hoffmann-aeropress-rec...

I like the button idea. 1. I'd love to see it battery powered. 2. I found a vape thing yesterday - I would love to see a battery from a Vape re-used if possible. 3. Lastly - based on a project I'm trying to do now. Can you somehow sleep the microcontroller so it uses no power while in standby and then starts the timer, so you have close to indefinite battery life?

rahimnathwani•2mo ago

Regarding the last point, you can do better than sleep (lower power state). You can have the microcontroller cut its own power once it's done its work:

https://randomnerdtutorials.com/latching-power-switch-circui...

jacknews•2mo ago

555

notpushkin•2mo ago

Came in for this joke.

ErroneousBosh•1mo ago

You can't use a 555, obviously.

You need to use two of them, or a 556, because you need one half for the 30 second monostable and the other half for the astable that drives the beeper.

Out of contrariness I'd use a CD4011 though.

jacknews•1mo ago

You're right, but I think a 555 is maybe more than required for the buzzer.

Buzz-overkill, if you like.

bsoles•2mo ago

Driving a buzzer directly from the GPIO pin will probably fry the output port if the buzzer draws anything more than about 20-50 mA.

duskwuff•2mo ago

Small piezo beepers typically don't draw much current. The article doesn't say what part they're using, but a datasheet for a typical piezo beeper [1] says it draws 12 mA at 12V - and much less at 3.3V, which is what this device is operating at. So it's probably going to be fine, especially since it's only running the buzzer for <50 ms at a time.

[1]: https://www.mouser.com/datasheet/3/6118/1/cpe_350a.pdf

vanous•2mo ago

> error-prone to set a 30-second timer. Oops, I’m tired and I hit zero too many times. That’s a 3-minute (3:00) timer. I typed in 3-0 correctly, but hitting the start button didn’t quite register. Siri misheard. Siri took 10 seconds to respond about a 30 second timer.

I get the diy factor, but still, the smartphone was supposed to be smart...

N_Lens•2mo ago

A bit of a 'diwhy' when you can buy a simple spring loaded twist timer for $2-5

thenthenthen•2mo ago

Or a spinning top? :D

throwaway81523•2mo ago

My trick is to re-use the filters. After the first few presses, the filters clog up somewhat and coffee doesn't drip through them as fast. So you can stir and let the mixture sit for a while, without resorting to maneuvers like the inverted method, which are unsafe for groggy programmers who haven't had any coffee yet that morning.

But, I thought Arduino had become officially evil once it joined Qualcomm. Besides which a Raspberry Pi Pico is cheaper than any Arduino-branded board ever was. So I'd just program this type of thing in MicroPython.

I do see that in the article, the project used an Adafruit Trinket M0, a very cute little board that has CircuitPython already installed. So I wonder why not just use CircuitPython. Anyway though, it's a Cortex M0 board, rather than the traditional Atmega that the Arduino world grew up using.

finaard•2mo ago

> But, I thought Arduino had become officially evil once it joined Qualcomm.

They have - but for less technical users their IDE is not too bad, and there are way too many bits out there relying on it, including lots of stuff not arduino, plus it's open source. And as it reloads files on changes can be used with a real editor as well. So for the software side I'm inclined to stick with that thing.

For hardware side it's different - but every interesting arduino has shitloads of clones available. In the past I've been buying those only for special use cases where there were no genuine arduinos to support the project - now since they got crazy it's only clones, and whenever I touch any of my old projects I'm updating the list of materials to recommend buying clones. You can still get nano clones for just a bit over 1 EUR each, so for projects where that is enough that's hard to beat value for the money.

throwaway81523•2mo ago

Tbh the 30 second timer project probably could have been done with the legendary Padauk 3 cent mcu.

benbojangles•2mo ago

What happens if you replace aeropress with dynamite

OpenCiv3: Open-source, cross-platform reimagining of Civilization III

The Waymo World Model

How we made geo joins 400× faster with H3 indexes

Show HN: Look Ma, No Linux: Shell, App Installer, Vi, Cc on ESP32-S3 / BreezyBox

Monty: A minimal, secure Python interpreter written in Rust for use by AI

Show HN: I spent 4 years building a UI design tool with only the features I use

Dark Alley Mathematics

Microsoft open-sources LiteBox, a security-focused library OS

Sheldon Brown's Bicycle Technical Info

Hackers (1995) Animated Experience

Show HN: If you lose your memory, how to regain access to your computer?

An Update on Heroku

Delimited Continuations vs. Lwt for Threads

PC Floppy Copy Protection: Vault Prolok

Unseen Footage of Atari Battlezone Arcade Cabinet Production

How to effectively write quality code with AI

Show HN: ARM64 Android Dev Kit

Why I Joined OpenAI

Show HN: R3forth, a ColorForth-inspired language with a tiny VM

Learning from context is harder than we thought

Introducing the Developer Knowledge API and MCP Server

I spent 5 years in DevOps – Solutions engineering gave me what I was missing

Female Asian Elephant Calf Born at the Smithsonian National Zoo

Understanding Neural Network, Visually

I now assume that all ads on Apple news are scams

FORTH? Really!?

Show HN: Smooth CLI – Token-efficient browser for AI agents

WebView performance significantly slower than PWA

Zlob.h 100% POSIX and glibc compatible globbing lib that is faste and better

I'm going to cure my girlfriend's brain tumor