2025 One Hertz Challenge: 555 Timer Gets A Signal From Above

July 24, 2025 by Adam Zeloof 6 Comments

One of the categories we chose for the One Hertz Challenge is “Could Have Used a 555.” What about when you couldn’t have, but did anyway? The 555 is famously easy to use, but not exactly the most accurate timer out there — one “ticking” at 1 Hz will pulse just about once per second (probably to within a millisecond, depending on the rest of the circuit), but when you need more precise timing, the 555 just won’t cut it. Not on its own, anyway.

An Allan deviation plot — Allan Deviation can be a bit confusing, but generally — lower is more accurate

This entry by [burble] shows us how the humble 555 can hold its own in more demanding systems with some help from a GPS receiver. He used the One Pulse per Second (1PPS) output from a GPS module to discipline the 1 Hz output from a 555 by modulating the control voltage with a microcontroller.

Okay, this sounds a bit like baking a cake by buying a cake, scraping all the icing off, then icing it yourself, but what better way to learn how to ice a cake? The GPS-disciplined 555 is way more accurate than a free running one — just check out that Allan Deviation plot. While the accuracy of the standard 555 begins to decrease as oscillator drift dominates, the GPS-disciplined version just keeps getting better (up to a point — it would also eventually begin to increase, if the data were recorded for long enough). Compared to other high-end oscillators though, [burble] describes the project’s accuracy in one word: “Badly.”

That’s okay though — it really is a fantastic investigation into how GPS-disciplined oscillators work, and does a fantastic job illustrating the accuracy of different types of clocks, and some possible sources of error. This project is a great addition to some of the other precision timekeeping projects we’ve seen here at Hackaday, and a very fitting entry to the competition. Think you can do better? Or much, much worse? You’ve got a few weeks left to enter!

South Australia Vs. Too Much Home Solar

May 10, 2021 by Lewin Day 209 Comments

Once upon a time, the consensus was that renewable energy was too expensive and in too sparse supply to be a viable power source to run our proud, electrified societies on. Since then, prices of solar panels have tanked, becoming more efficient along the way, and homeowners have been installing them on their rooftops in droves.

Where once it was thought we’d never have enough solar energy, in some cities, it’s becoming all too much. In South Australia, where solar output can be huge on a sunny day, electricity authorities are facing problems with grid stability, and are taking measures to limit solar output to the grid.

Isn’t More Usually Better?

The problem faced by South Australian utilities is one of how to properly control an electrical grid with many thousands of distributed power sources. Typically, in conventional modern power grids, voltage and frequency is controlled within set limits by carefully matching the supply from major power plants with the demand from users. Fast-response plants can be brought online to meet shortfalls, and switched off when demand drops, and everything hums along nicely.

Unfortunately, solar power isn’t so easy to throttle, and even less so when it’s coming from thousands of separate households each with their own rooftop install and an inverter to feed back into the grid. This has led to authorities contemplating measures such as charging homeowners to export energy to the grid in peak periods in an effort to slow the huge uptake of home solar systems. Export limits have also been proposed for suburbs with the highest concentration of home solar, as substations in certain residential areas struggle to cope under the huge inflows of energy. Continue reading “South Australia Vs. Too Much Home Solar” →

Apparently Time IS Money

April 13, 2017 by Al Williams 25 Comments

Some people like to tweak cars. Some like to overclock PCs. Then there are the guys like [Jack Zimmermann] who are obsessed with accurate time. He’s working on a project that will deploy NTP (Network Time Protocol) servers in different African countries and needed small, cheap, energy-efficient, and accurate servers. What he wound up with is a very accurate setup for around $200. Along the way, he built some custom hardware, and hacked a computer to sync to the GPS clock reference.

His original attempt was with a Raspberry Pi 3. However, the network adapter isn’t the fastest possible, both because it is 100 MBPS and, primarily, because it is connected via the USB bus. Network latency due to these limitations makes it difficult to serve accurate time.

His solution includes an Odroid C2. For $50 it is a very capable computer with four cores, gigabit Ethernet, and can even use eMMC storage which is faster than the usual SD card. You can still use a conventional SD card, though, if you prefer.

Continue reading “Apparently Time IS Money” →