Day: July 11, 2024

You Can Use A CRT As An Audio Amplifier Tube

July 11, 2024 by 36 Comments

When we talk about audio amplifier tubes, we’re normally talking about the glass little blobby things you might find in a guitar amplifier. We’re not normally talking about big ol’ color CRTs, but apparently they can do the job too. That’s what [Termadnator] is here to show us.

The CRT in question is a 14″ unit from a common garden variety Philips color TV.  [Termadnator] pulled out the TV’s original circuitry, and replaced much of it with his own. He had to whip up a high-voltage power supply with a 555 and a laptop power supply, along with a bunch of fake MOSFETs pressed into service. He also had to build his own Leyden jar capacitor, too. The specifics of converting it to audio operation get a bit messy, but fear not—[Termadnator] explains the idea well, and also supplies a schematic. Perhaps the coolest thing, though, is the crazy color pattern that appears on the display when it’s working as an amp.

Sound output isn’t exactly loud, and it’s a little distorted, too. Still, it’s amusing to see an entire TV instead doing the job of a single amplifier tube. Video after the break.

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Why The 555 Is Not A Timer, But Can Be One

July 11, 2024 by 31 Comments

Although commonly referred to as a ‘timer IC’, the venerable NE555 and derivatives are in fact not timer ICs. This perhaps controversial statement is the open door that gets kicked in by [PKAE Electronics] over at YouTube, as he explains with excellent diagrams and simulations how exactly these ICs work, and what it takes to make it actually do timer things. For anyone who has ever used one of these chips there is probably nothing too mind-blowing, but it’s an infinitely better way to wrap your way around an NE555 and kin than a datasheet.

At its core, the 555 contains three 5 kOhm resistors as a voltage divider, which has been incorrectly postulated to be the source of the chip’s name. This voltage divider controls two comparators, which in turn control an SR flipflop. These comparators are used for the voltage trigger and threshold inputs, which in turn toggle the flipflop, respectively setting and resetting it. This by itself just means that the 555 can be used as a threshold detector, with settable control voltage. How a 555 becomes a timer is when the discharge, trigger and threshold pins are combined with external resistors and a capacitor, which creates a smooth square wave on the 555’s output pin.

There are many ways to make basic components into an oscillator of some type, but the 555 is a great choice when you want something more refined that doesn’t involve using an entire MCU. That said, there’s far more that the 555 can be used for, as [PKAE] alludes to, and we hope that he makes more excellent videos on these applications.

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Build Your Own Hydroelectric Dam

July 11, 2024 by 21 Comments

We have to admit that we often think about building unusual things, but we hadn’t really considered building our own hydroelectric dam before. [Mini Construction] did, apparently, and there’s a timelapse of the build in the video below.

We wished this was more of a how-to video, although if you are handy with brickwork, the mechanical construction seems straightforward. Presumably, you’d need to understand how much force the water had but we don’t know if there was math involved or just seat-of-the-pants design.

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Newly Completed Overly-Complex Clock Synchronizes Multiple Mechanisms

July 11, 2024 by 1 Comment

Some time ago [Kelton] was working on a clock inspired by Rube Goldberg contraptions. It uses only a single motor, and he’s proud to now show off the finished product (video, embedded below.)

The clock shows hours on the left, and minutes on the right. Every sixty minutes the clock drops a marble. That marble kicks off a series of visually-satisfying operations that culminate in advancing the hour. Then everything resets, and it continues for as long as it has power.

The hour oscillates in a very satisfying manner as it locks in.

At the top of each hour, the minute hand tips a marble with a gravity cam. That marble runs down a track gaining enough momentum to flip a kicker, and a short series of falling dominoes builds enough force to tip and trigger the spring-loaded ratchet that locks in a new hour. You can skip directly to 2:09 if you just want to listen to [Kelton] explain the whole operation from beginning to end.

We think it’s very interesting to note that this clock’s complexity is, if anything, understated. Each of the mechanisms involved must individually reset by their own separate mechanisms, each of which are as intriguing as their showier counterparts, and we’re sure they were every bit as difficult to get just right. And of course, it’s all driven by a single motor.

You may recall the promising start this clock project was off to and we’re delighted to see it come to completion, especially considering its complexity. Not every project sees completion, and fewer still get a version two, but that’s okay. What really floats our boat is seeing the process and details as well as hearing about what worked and what didn’t. We’re glad this clock reached the finish line, but even if something doesn’t work out, there’s always something to learn.

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A business card-sized synthesizer with capacitive touch pads.

2024 Business Card Challenge: The Gift Of Music

July 11, 2024 by 7 Comments

Has anyone ever told you that you just can’t carry a tune? If you were to be the lucky recipient of one of [Ayu]’s synthesizer business cards, well, then it really couldn’t be helped.

This tiny, go-anywhere instrument has quite a lot going for it. It’s easy for anyone to pick up and play something, but versatile enough that a more experienced musician can add complexity. While we do tend to see twelve keys in a small form-factor like this, the Canta-Cart uses them a bit differently. Only ten are tied to notes, and the other two are for transposition.

[Ayu] was able to keep the BOM cost way down by using the PY32, which is an ARM Cortex-M microcontroller made by Puya that costs as little as 10¢ each. In fact, the whole BOM clocks in around 60¢ total even with the audio DAC and amplifier ICs, which really makes these ideal to actually give away to people. Check it out in action after the break, or try it in the browser!

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You Can Build A Little Car That Goes Farther Than You Push It

July 11, 2024 by 25 Comments

Can you build a car that travels farther than you push it? [Tom Stanton] shows us that you can, using a capacitor and some nifty design tricks.

[Tom]’s video shows us the construction of a small 3D printed trike with a curious drivetrain. There’s a simple generator on board, which charges a capacitor when the trike is pushed along the ground. When the trike is let go, however, this generator instead acts as a motor, using energy stored in the capacitor to drive the trike further.

When put to the test by [Tom], both a freewheeling car and the capacitor car are pushed up to a set speed. But the capacitor car goes farther. The trick is simple – the capacitor car can go further because it has more energy. But how?

It’s all because more work is being done to push the capacitor car up to speed. It stores energy in the capacitor while it’s being accelerated by the human pushing it. In contrast, after being pushed, the freewheeling car merely coasts to a stop as it loses kinetic energy. However, the capacitor car has similar kinetic energy plus the energy stored in its capacitor, which it can use to run its motor.

It’s a neat exploration of some basic physics, and useful learning if you’ve ever wondered about the prospects of perpetual motion machines.

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Embedded Python: MicroPython Is Amazing

July 11, 2024 by 104 Comments

In case you haven’t heard, about a month ago MicroPython has celebrated its 11th birthday. I was lucky that I was able to start hacking with it soon after pyboards have shipped – the first tech talk I remember giving was about MicroPython, and that talk was how I got into the hackerspace I subsequently spent years in. Since then, MicroPython been a staple in my projects, workshops, and hacking forays.

If you’re friends with Python or you’re willing to learn, you might just enjoy it a lot too. What’s more, MicroPython is an invaluable addition to a hacker’s toolkit, and I’d like to show you why. Continue reading “Embedded Python: MicroPython Is Amazing” →