As [Sam Ben-Yaakov] points out in a recent video, you don’t often see flyback converters these days. That’s because there are smarter ways to get the same effect, which is to convert between two voltages. If you work on old gear, you’ll see plenty of these, and going through the analysis is educational, even if you’ll never actually work with the circuit. That’s what the video below shows: [Sam’s] analysis of why this circuit works.
The circuit in question uses a bridge rectifier to get a high-voltage DC voltage directly from the wall. Of course, you could just use a transformer to convert the AC to a lower AC voltage first, but then you probably need a regulator afterwards to get a stable voltage.
You can use a microcontroller to build a clock. After all, a clock is just something that counts the passage of time. The only problem is that microcontrollers can’t track time very accurately. They need some kind of external timing source that doesn’t drift as much as the microcontroller’s primary clock oscillator. To that end, [Josh] wanted to try using a rather famous IC with his Arduino to build a viable timepiece.
[Josh]’s idea was straightforward—employ a 555 timer IC to generate a square wave at 1 Hz. He set up an Arduino Uno to count the pulses using edge detection. This allowed for a reliable count which would serve as the timebase for a simple 24-hour clock. The time was then displayed on an OLED display attached over I2C, while raw pulses from the 555 were counted on a 7-segment display as a useful debugging measure. Setting the time is easy, with a few pushbuttons hooked up to the Arduino for this purpose.
[Josh] claims a drift of “only ~0.5 seconds” but does not state over what time period this drift occurs. In any case, 555s are not really used for timekeeping purposes in this way, because timers based on resistor-capacitor circuits tend to drift a lot and are highly susceptible to temperature changes. However, [Josh] could easily turn this into a highly accurate clock merely by replacing the 555 square wave input with a 1PPS clock source from another type of timer or GPS device.
The build relies on an Inkplate e-paper screen as a display, which is probably as close you can get in appearance to the aluminium dust and glass screen used in an Etch-a-Sketch. The display is hooked up to an ESP32 microcontroller, which is charged with reading inputs from a pair of rotary encoders. In standard drawing mode, it emulates the behavior of an Etch-A-Sketch, with the ESP32 drawing to the e-paper display as the user turns the encoders to move the cursor. However, it has a magical “undo” feature, where pressing the encoder undoes the last movement, allowing you to craft complex creations without having to get every move perfect on your first attempt. As a fun aside, [Tekavou] also included a fun Snake game. More specifically, it’s inspired by NIBBLES.BAS, a demo program included with Microsoft QBasic back in the day.
We’ve seen all kinds of Etch-A-Sketch builds around these parts, including this impressive roboticized version. Video after the break.
The 2025 One Hertz Challenge asks you to build a project that does something once every second. While that has inspired a lot of clock and timekeeping builds, we’re also seeing some that do entirely different things on a 1 Hz period. [junkdust] has entered the contest with a project that does something rather mathematical once every second.
[junkdust] wanted to get better acquainted with the venerable ATtiny85, so decided to implement Conway’s Game of Life on it. The microcontroller is hooked up to a 0.91″ OLED display with a resolution of 128 x 32 pixels, however, [junkdust] only elected to implement a 32 x 32 grid for the game itself, using the rest of the display area to report the vital statistics of the game. On power up, the grid is populated with a random population, and the game proceeds, updating once every second.
It’s a neat little desk toy, but more importantly than that, it served as a nicely complicated test project for [junkdust] to get familiar working inside the limitations of the ATtiny85. It may be a humble part, but it can do great things, as we’ve seen many times before!
We’re back! This week Jonathan chats with Mattias Wadman and Michael Farber about JQ! It’s more than just a JSON parser, JQ is a whole scripting language! Tune in to find out more about it.
When do you think the first podcast occurred? Did you guess in the 1890s? That’s not a typo. Telefonhírmondó was possibly the world’s first true “telephone newspaper.” People in Budapest could dial a phone number and listen to what we would think of now as radio content. Surprisingly, the service lasted until 1944, although after 1925, it was rebroadcasting a radio station’s programming.
Tivadar Puskás, the founder of Budapest’s “Telephone Newspaper” (public domain)
The whole thing was the brainchild of Tivadar Puskás, an engineer who had worked with Thomas Edison. At first, the service had about 60 subscribers, but Puskás envisioned the service one day spanning the globe. Of course, he wasn’t wrong. There was a market for worldwide audio programs, but they were not going to travel over phone lines to the customer.
The Hungarian government kept tight control over newspapers in those days. However, as we see in modern times, new media often slips through the cracks. After two weeks of proving the concept out, Puskás asked for formal approval and for a 50-year exclusive franchise for the city of Budapest. They would eventually approve the former, but not the latter.
Unfortunately, a month into the new venture, Puskás died. His brother Albert took over and continued talks with the government. The phone company wanted a piece of the action, as did the government. Before anything was settled, Albert sold the company to István Popper. He finalized the deal, which included rules requiring signed copies of the news reports to be sent to the police three times a day. The affair must have been lucrative. The company would eventually construct its own telephone network independent of the normal phone system. By 1907, they boasted 15,000 subscribers, including notable politicians and businesses, including hotels. Continue reading “The World’s First Podcaster?”→
Facing the horrifying realization that he’s going to graduate soon, EE student [Colin Jackson] AKA [Electronics Guy] needed a business card. Not just any business card: a PCB business card. Not just any PCB business card: a PCB business card that can play pong.
[Colin] was heavily inspired by the card [Ben Eater] was handing out at OpenSauce last year, and openly admits to copying the button holder from it. We can’t blame him: the routed-out fingers to hold a lithium button cell were a great idea. The original idea, a 3D persistence-of-vision display, was a little too ambitious to fit on a business card, so [Colin] repurposed the 64 LED matrix and STM32 processor to play Pong. Aside from the LEDs and the microprocessor, it looks like the board has a shift register to handle all those outputs and a pair of surface-mount buttons.
Of course you can’t get two players on a business card, so the microprocessor is serving as the opponent. With only 64 LEDs, there’s no room for score-keeping — but apparently even the first, nonworking prototype was good enough to get [Colin] a job, so not only can we not complain, we offer our congratulations.
