Should’ve Used A 555 — Or 276 Of Them

August 10, 2022 by Dan Maloney 33 Comments

When asked to whip up a simple egg timer, most of us could probably come up with a quick design based on the ubiquitous 555 timer. Add a couple of passives around the little eight-pin DIP, put an LED on it to show when time runs out, and maybe even add a pot for variable timing intervals if we’re feeling fancy. Heck, many of us could do it from memory.

So why exactly did [Jesse Farrell] manage to do essentially the same thing using a whopping 276 555s? Easy — because why not? Originally started as an entry in the latest iteration of our 555 Contest, [Jesse]’s goal was simple — build a functional timer with a digital display using nothing but 555s and the necessary passives. He ended up needing a few transistors and diodes to pull it off, but that’s a minor concession when you consider how many chips he replaced with 555s, including counters, decoders, multiplexers, and display drivers. All these chips were built up from basic logic gates, a latch, and a flip-flop, all made from one or more 555s, or variants like the 556 or 558.

As one can imagine, 276 chips take a lot of real estate, and it took eleven PCBs to complete the timer. A main board acts as the timer’s control panel as well as serving as a motherboard for ten other cards, each devoted to a different block of functions. It’s all neat and tidy, and very well-executed, which is in keeping with the excellent documentation [Jesse] produced. The whole thing is wonderfully, needlessly complex, and we couldn’t be more tickled to feature it.

Continue reading “Should’ve Used A 555 — Or 276 Of Them” →

Electronic Dice Is Introduction To Microcontroller Programming

May 27, 2022 by Bryan Cockfield 10 Comments

By now most of us are familiar with the Arduino platform. It’s an inexpensive and fairly easy way into the world of microcontrollers. For plenty of projects, there’s no need to go beyond that unless you have a desire to learn more of the inner workings of microcontrollers in general. [Cristiano] was interested in expanding some of his knowledge, so he decided to build this electronic dice using a PIC microcontroller instead of the Arduino platform he was more familiar with.

As a result, this project is set up as a how-to for others looking to dive further into the world of microcontrollers that don’t have the same hand-holding setup as the Arduino. To take care of the need for a random number for the dice, the PIC’s random number generator is used but with the added randomness of a seed from an internal timer. The timer is started when a mercury tilt switch signals the device that it has been rolled over, and after some computation a single digit number is displayed on a seven-segment display.

While it might seem simple on the surface, the project comes with an in-depth guide on programming the PIC family of microcontrollers, and has a polish not normally seen on beginner projects, including the use of the mercury tilt switch which gives it a retro vibe. For some other tips on how to build projects like this, take a look at this guide on how to build power supplies for your projects as well.

Continue reading “Electronic Dice Is Introduction To Microcontroller Programming” →

Track Those Leftovers With This Little Timer

May 1, 2022 by Jenny List 28 Comments

We’ve all at some point in our lives opened the fridge door and immediately wished we hadn’t. A miasma of stench envelops us as we discover that last Saturday’s leftovers have been forgotten, and have gone off. If only we had some way to keep track of such things, to avoid such a stench-laden moment. Step forward [ThinkLearnDo], with a little timer designed for exactly that purpose.

The operation is simple enough, press the button and place the unit on top of the container with the leftovers in it. If you haven’t eaten the leftovers within a week, the LED will start blinking. The blink is a subtle reminder to deal with the old food before it becomes a problem.

Onboard is a Holtek HT68F001 microcontroller with a coin cell for power, not much else is needed. The Holtek is an unusual choice, one of several brands of super-inexpensive Chinese microcontrollers we see less commonly than ATmegas and STM32s. This is exactly the place where such a minimal computer fits perfectly: a way to add a little bit of smarts to a very cheap item with minimal strain on the BoM.

If these chips interest you, a while back we covered a run-down of the different families including the Holtek and the famous 3-cent Padauk chips.

Custom Controller Ups Heat Pump Efficiency

March 25, 2022 by Bryan Cockfield 59 Comments

Heat Pumps are an extremely efficient way to maintain climate control in a building. Unlike traditional air conditioners, heat pumps can also effectively work in reverse to warm a home in winter as well as cool it in summer; with up to five times the efficiency of energy use as a traditional electric heater. Even with those tremendous gains in performance, there are still some ways to improve on them as [Martin] shows us with some modifications he made to his heat pump system.

This specific heat pump is being employed not for climate control but for water heating, which sees similar improvements in efficiency over a standard water heater. The problem with [Martin]’s was that even then it was simply running much too often. After sleuthing the energy losses and trying a number of things including a one-way valve on the heating water plumbing to prevent siphoning, he eventually found that the heat pump was ramping up to maximum temperature once per day even if the water tank was already hot. By building a custom master controller for the heat pump which includes some timing relays, the heat pump only runs up to its maximum temperature once per week.

While there are some concerns with Legionnaire’s bacteria if the system is not maintained properly, this modification still meets all of Australia’s stringent building code requirements. His build is more of an investigative journey into a more complex piece of machinery, and his efforts net him a max energy usage of around 1 kWh per day which is 50% more efficient than it was when it was first installed. If you’re looking to investigate more into heat pumps, take a look at this DIY Arduino-controlled mini heat pump.

Continue reading “Custom Controller Ups Heat Pump Efficiency” →

555 Timer On Its Own In Electronic Dice

January 8, 2022 by Bryan Cockfield 18 Comments

One of the most common clichés around here is that a piece of equipment chosen for a project is always too advanced. If a Raspberry Pi was used, someone will say they should have used an Arduino. If they use an Arduino, it should have been an ATtiny. And of course, if an ATtiny was used, there should have simply been a 555 timer. This time, however, [Tim] decided to actually show how this can be done by removing some of the integrated circuits from an electronic dice and relying entirely on the 555 timer for his build.

The electronic dice that [Tim] has on hand makes use of two main ICs: a NE555 and a CD4017 which is a decade counter/divider used for cycling through states. In order to bring the 555 to the forefront of this build, he scraps the CD4017 and adds an array of 555 timers. These are used to generate the clock signals necessary for this build but can also be arranged to form logic circuits. This comes at a great cost, however. The 555 chips take up an unnecessarily large area on the PCB (even though these are small surface-mount chips), consume an incredible amount of power, and are very slow. That’s fine for an electronic dice-rolling machine like this one, but that’s probably where [Tim] will leave this idea.

The 555 timer is a surprisingly versatile chip, and this project shows that there is some element of truth to the folks claiming that projects need naught but a few 555s. We’ve seen entire CPUs built using nothing but 555s, and even a classic project that uses a 555 timer to balance a robot.

Significantly Improved Egg Timer Makes Pictionary Better

November 23, 2021 by Lewin Day 24 Comments

The traditional sand timer, known colloquially as an egg timer, served its purpose well over the centuries since its development. However, [MakerPaul] realised it had some significant flaws that were ruining Pictionary, and set out to fix the problem.

If you’re not looking directly at an egg timer, it’s easy to miss the moment when the timer runs out. Resetting the timer before it runs out also requires waiting for the sand to filter to one side. Clearly the world needs a better mousetrap.

The tipping timer from [MakerPaul] solves both those issues. In this design, sand flows down into an offset area, which tips the device over when reaching a certain time limit. Additionally, turning the device upside down and then rotating it instantly reloads the sand, meaning the timer can be reused immediately.

[MakerPaul] first came up with the idea about 20 years ago, refining it during the recent lockdowns. The design files are freely available for anyone that wishes to build one. [MakerPaul] isn’t commercializing the idea, but mentions that it would be great if anyone using it makes a donation to the Mind mental health charity.

Most timers we feature are electronic and digital, but it’s easy to appreciate the elegance of what [MakerPaul] has achieved here. As a bonus, he documented the entire project and its application in under 90 seconds. How good is that? Video after the break.

Continue reading “Significantly Improved Egg Timer Makes Pictionary Better” →

Minimalist Timer Counts Down With LED Matrix

October 1, 2021 by Tom Nardi 3 Comments

Looking for something with a bit more style than the traditional kitchen timer, [Martin Jonasson] decided to take the last couple of months to design and build his own take on the idea using a rotary encoder, 16×9 LED matrix, and a Teensy 2.0 microcontroller. Were there better things he could have spent that time on? Possibly. But you probably wouldn’t have been reading it about it here, so we won’t trouble ourselves with such thoughts.

Put together on a piece of perfboard, the handwired circuit also includes an Adafruit PowerBoost 500 Charger, a 3.7 V 2500 mAh LiPo battery, a IS31FL3731 Charlieplexed PWM LED driver, and a piezo buzzer. The top of the rotary encoder has been capped off with a sold metal knob, which combined with the enclosure made of stacked laser cut 3 mm acrylic sheets, really gives the device a very sleek and classy look.

While the hardware is quite nice, it’s the software that really pulls this whole project together. A game developer by trade, [Martin] went all in on the timer’s GPLv3 licensed firmware. From using the toneAC library to play melodies at the end of the countdown, to the custom fonts and the code that pauses the timer while the user is spinning the knob, there’s plenty of little touches that should make the timer a joy to use. We’ve seen some unique kitchen timers over the years, but the attention to detail put into this build really raises the bar.

[Martin] has provided everything you need to create your own version of his timer, including the SVG file for the laser cut case. While not strictly required, coming up with a custom PCB for this project would be a nice touch, should you want to put your own spin on it.

[Thanks to Tom for the tip.]