An ATTiny GPU Fan Controller That Sticks

August 2, 2025 by Heidi Ulrich 12 Comments

When your GPU fan goes rogue with an unholy screech, you either shell out for a new one or you go full hacker mode. Well, [ashafq] did the latter. The result is a delightfully nerdy fan controller powered by an ATTiny85 and governed by a DS18B20 temperature sensor. We all know a silent workstation is golden, and there’s no fun in throwing money at an off-the-shelf solution. [ashafq]’s custom build transforms a whiny Radeon RX 550 into a cool, quiet operator. Best of all: it’s built from bits likely already in your junk drawer.

To challenge himself a bit, [ashafq] rolled his own temperature-triggered PWM logic using 1-wire protocol on an ATtiny85, all without libraries or bloated firmware. The fan’s speed only ramps up when the GPU gets toasty, just like it should. It’s efficient and clever, and that makes it a fine hack. The entire system runs off a scavenged 12V fan. He could have used a 3D printer, but decided to stick onto the card with double-sided tape. McGyver would approve.

The results don’t lie: idle temps at 40 °C, load peaking at 60 °C. Quieter than stock, smarter than stock, and way cheaper too. The double-sided tape may not last, but that leaves room for improvement. In case you want to start on it yourself, read the full write-up and feel inspired to build your own. Hackaday.io is ready for the documentation of your take on it.

Modifying fans is a tradition around here. Does it always take a processor? Nope.

CIS-4 Is A Monkish Clock Inside A Ceiling Lamp

July 4, 2025 by Tyler August 2 Comments

It’s always clock time at Hackaday, and this time we have an interesting hack of a clock by [danjovic]– the CIS4, a Cistercian digital clock.

The Cistertians, in case you weren’t paying close attention to European holy orders during the 13th to 15th centuries were the group of monks you’d most likely have found us in. They were the hackers of the middle ages, establishing monestaries across western Europe that were chock full of hacks– including their own numeral system. Cistercian numerals were much more efficient (in spaces and penstrokes) than the Roman numerals they replaced, and even the “Arabic” numerals that replaced them. A single glyph could record anything from 1 to 9,999. (The Europeans hadn’t yet cottoned on to zero.)

The Cistertian glyphs reduced to a 4×4 display.

Depending how you wanted to count time, a single glyph could be used; it looks like [danjovic] is using the thousands and hundreds portions of the glyph for hours and the tens and ones for minutes. This is all accomplished with a 4×4 neopixel matrix, run by an Attiny85 Digispark with a DS3231 RTC module keeping time. A slight simplification is required to reduce the glyphs to 4×4, but we don’t think the monks would mind. For those of us who don’t wear tonsures, an easy read mode scrolls the time in Arabic numerals. (Which still aren’t super easy,with only 4×4 LEDs to display them. See the demo video embedded below and try and guess the time.)

One nice quality of life feature is an LDR for ambient light detection, to automatically adjust the neopixels’ brightness. The hackiest part, which we thought was really clever, is the enclosure: it’s a cheap LED ceiling light. This provides a diffuser, housing and mounting hardware with decent design for no effort. A 3D-printed mask sits between the diffuser and the LEDs and doubles as a PCB holder. All very elegant.

[danjovic] did include a buzzer in the design, but does say if its been programed to sound off for matins, nones and vespers. In any case, at least it’s easier to read than his binary-coded-octal clock that we featured a few years back. This isn’t our first look at this number system,so evidently people can read them with practice.

Have you made or seen a cool clock? Send us a tip. We always have time for clocks. Continue reading “CIS-4 Is A Monkish Clock Inside A Ceiling Lamp” →

LED Probe: A Smart, Simple Solution For Testing LEDs

June 14, 2025 by Matt Varian 13 Comments

If you’ve worked on a project with small LEDs, you know the frustration of determining their polarity. This ingenious LED Probe from [David] packs a lot of useful features into a simple, easy-to-implement circuit.

Most multimeters have a diode test function that can be used to check LEDs; however, this goes a step further. Not only will the probe light up an LED, it will light up no matter which side of the LED the leads are touching. A Red/Green LED on the probe will indicate if the probe tip is on the anode or cathode.

The probe is powered by a single CR2032 battery, and you may notice there’s no on/off switch. That’s because the probe enters a very low-current sleep mode between uses. The testing intelligence is handled by either an ATtiny85 or, in the newest version, an ATtiny202, though the basic concept and design are compatible with several other chips. All the design files for the PCB, the ATtiny code, a parts list, and a detailed explanation of how it works are available on [David]’s site, so be sure to check them out. Once you build one of these probes, you’ll want something to test it on, so explore some of the LED projects we’ve featured in the past.

This Thermometer Rules!

February 5, 2025 by Jenny List 9 Comments

A PCB ruler is a common promotional item, or design exercise. Usually they have some sample outlines and holes as an aid to PCB design, but sometimes they also incorporate some circuitry. [Clovis Fritzen] has given us an ingenious example, in the form of a PCB ruler with a built-in thermometer.

This maybe doesn’t have the fancy seven segment or OLED display you were expecting though, instead it’s an ATtiny85 with a lithium cell, the minimum of components, a thermistor for measurement, and a couple of LEDs that serve as the display. These parts are interesting, because they convey the numbers by flashing. One LED is for the tens and the other the units, so count the flashes and you have it.

We like this display for its simplicity, we can see the same idea could be used in many other places.On a PCB ruler, it certainly stands apart from the usual. It has got plenty of competition though.

Gas Gauge Upgrade Keeps VW Restoration Classy

December 4, 2024 by Dan Maloney 49 Comments

Getting every detail perfectly right is often the goal in automotive restorations, and some people will go to amazing lengths to make sure the car looks and acts just like it did when it rolled off the dealer’s lot all those decades ago. That ethos can be pushed a little too far, though, especially with practical matters like knowing how much gas is left in the tank. Get that wrong and you’ll be walking.

Unwilling to risk that cruel fate with his restoration of 1978 Volkswagen Bus, [Pegork] came up with a replacement fuel gauge that looks identical to the original meter, but actually works. The gas gauges on ’60s and ’70s VWs were notoriously finicky, and when they bothered to work at all they were often wildly inaccurate. The problem was usually not with the sender unit in the tank, but the gauge in the dash, which used a bimetallic strip heated by a small coil of wire to deflect a needle. [Pegor]’s “SmoothBus” modification replaces the mechanical movement with a micro servo to move the needle. The variable voltage coming back from the fuel sender is scaled through a voltage divider and read by an analog input on an ATtiny85, which does a little algorithmic smoothing to make sure the needle doesn’t jump around too much. A really nice addition is an LED low fuel indicator, a feature that would have saved us many walks to the gas station back in our VW days. Except for the extra light, the restored gauge looks completely stock, and it works far better than the original.

Hats off to [Pregor] for this fantastic restomod. As we’ve noted before, classic VWs are perhaps the most hackable of cars, and we applaud any effort to keep these quirky cars going.

Left: the ATtinyBoy and cartridges inside a custom case. Right: ATTinyBoy under the hood.

2024 Tiny Games Contest: ATtinyBoy Does It With Tiny Cartridges

August 31, 2024 by Kristina Panos 3 Comments

What is it about tangible media? There’s just something neat about having an individual thing that represents each game, each album, each whatever. Sure, you can have a little console with a thousand games loaded on it, but what’s the fun in that?

Enter the ATtinyBoy. [Bram]’s entry into the Tiny Games Contest is based on the ATtiny85, and the whole thing is smaller than a credit card. In fact, each little game cartridge contains its own ATtiny85, with the pins broken out into headers.

That is, although the schematic is based on [Billy Cheung]’s gametiny, which uses an ATtiny85 as the brain, ATtinyBoy’s brain is divided among each of the games.

This certainly checks a lot of boxes when it comes to contest rules and requirements, and it’s just awesome besides. We particularly like the custom box that holds ATtinyBoy and all his distributed knowledge. If you want to make one of your own, the schematic, code, and STLs are all available over on IO.

Nice Retro Displays Set This Watch On Edge

August 27, 2024 by Dan Maloney 10 Comments

A common design language for watches has evolved ever since they first started popping up in the 1500s. Whether worn on the wrist or in a pocket, watches are relatively slim front to back, with the display mounted on the face. That’s understandable given the imperatives of human anatomy. Still, it’s not the only way to arrange things, as this very cool LED matrix watch with an edge-mounted display demonstrates.

True, the unique form factor of this watch wasn’t really the point of the whole project. Rather, [Vitali]’s design was driven by a couple of things. First off were the extremely cool Hewlett Packard HDSP-2000 displays, with four ~~5×5~~ 5×7 LED matrices shining through the clear cover of a DIP-12 package. Also visible through the cover are the shift registers that drive the matrices, complete with gold bonding wires.

The main attraction for [Vitali], though, was the challenge of working within the limits of the ATtiny85 he chose to run the watch. The MCU’s limited IO made hardware multiplexing necessary, no mean feat given the limited resources and real estate available. He still managed to pack everything in, with the unique edge-mount display coming from the LEDs bridging the space between the two main PCBs. Everything fits into a nice wood veneer case, although we think it looks just fine without it. [Vitali] puts it through its paces in the short video below.

Hats off to [Vitali] for a great-looking project that pushed his limits. We just love these displays, too; of course, it’s not the first time we’ve seen them put to similar use.

Continue reading “Nice Retro Displays Set This Watch On Edge” →