An ESP In Your Mini TV

When miniature LCD TVs arrived on the market they were an object of desire, far from the reach of tech-obsessed youngsters. Now in the age of smartphones they’re a historical curiosity, but with the onward march of technology you can have one for not a lot. [Taylor Galbraith] shows us how, with an ESP32 and an LCD we rather like because of its CRT-like rounded corners.

What he’s created is essentially a small media player, but perhaps what makes it of further interest is its migration from a mess of wires on a breadboard to a rather nice PCB. He’s not released the board files at the time of writing, but since the software can all be found in the GitHub repository linked above, we live in hope. On it are not only the ESP and the screen, but also a battery management board, an audio amplifier, and a small speaker. For now it’s a bare board, but we hope he’ll complete it with a neatly designed case for either a pocket player or a retro-styled mini TV. Until then you can see his progress in the videos below the break.

If you’re after more ESP32 media player inspiration, this isn’t the first retro-themed media player we’ve brought you.

Continue reading “An ESP In Your Mini TV”

Know Audio: Distortion Part One

If you follow audiophile reviewers, you’ll know that their stock-in trade is a very fancy way of saying absolutely nothing of quantifiable substance about the subject while sounding knowledgeable about imagined differences between devices that are all of superlative quality anyway. If you follow us, we’ll tell you that the only reviews that matter are real-world measurements of audio performance, and blind listening tests. We don’t have to tell you how to listen to music, but perhaps it’s time in our Know Audio series to look at how audio performance is measured.

Before reaching for the bench, it’s first necessary to ask just what we are measuring. What are the properties which matter in an audio chain, or in other words, just what is it that makes an audio device good?

Continue reading “Know Audio: Distortion Part One”

Prison TV Gets Simple Speaker Mod

American prisons are strict about television use. Typically they’re only to be used with headphones, and their enclosures need to be transparent so they can’t be used to smuggle goods. ClearTech makes TVs that meet these specifications, and when [Steve Pietras] got his hands on just such a unit, he set about modding it for use in the free world.

Getting into the TV isn’t easy; ClearTech built the units using special security fasteners unlike any we’ve seen before. [Steve] found a way to deal with these, though declines to share his technique in his video. Once inside though, his task is relatively straightforward. He steps through where to install speakers in the TV’s housing, and how to hook them up to the right spots on the main circuit board. With the case closed back up, [Steve] is able to use the TV without headphones, and without the threat of getting shanked by a fellow inmate who really doesn’t want to hear Jeopardy while they’re trying to read.

It’s not every day we get to look at a piece of obscure hardware like this. We’d never seen a prison TV before, and now we feel like experts on the topic. Of course, we’re no strangers to esoterica at Hackaday.

Continue reading “Prison TV Gets Simple Speaker Mod”

No Home Cinema Is Complete Without A Motorized Projector

In the home of the future, everything is automated. Some of us are already there, in dwellings fully tricked-out with IoT and smart home devices. But they don’t somehow look as futuristic as a home in which everything is motorized. We don’t know whether this was the intention, but we certainly get a futuristic vibe from [Sam Baker]’s home cinema projector mount. It’s no mere bracket, instead on command the projector descends from concealment in the ceiling on a custom scissor lift mechanism.

A scissor lift is a simple enough mechanism, but since he was 3D printing one that had to withstand the weight of the projector, it took him a while to get it right. Even the lead screw which drives it is also printed, turned by a stepper motor. As the brains of the unit needn’t be particularly accomplished, an Arduino Nano does the job well enough.

It’s fair to say that his projector isn’t the heaviest of models, but the result glides smoothly down from the ceiling for a perfect home cinema experience. We like it.

It’s Difficult To Read An Audiophile Guide As An Analogue Engineer

Sitting on a train leaving the Hackaday Berlin conference, and Hacker News pops up Julian Shapiro with a guide to HiFi. What Hackaday scribe wouldn’t give it a click, to while away the endless kilometres of North European Plain!

It’s very easy as an analogue electronic engineer, to become frustrated while reading audiophile tracts, after all they have a tendency to blur superficial engineering talk with pseudoscience. There’s a rich vein of parody to be found in them, but nevertheless it’s interesting to read them because just sometimes the writer gets it and doesn’t descend into the world of make-believe. Continue reading “It’s Difficult To Read An Audiophile Guide As An Analogue Engineer”

A Look At Zweikanalton Stereo Audio And Comparison With NICAM

With how we take stereo sound for granted, there was a very long period where broadcast audio and television with accompanying audio track were in mono. Over the decades, multiple standards were developed that provide a way to transmit and receive two mono tracks, as a proper stereo transmission. In a recent video, [Matt] over at [Matt’s Tech Barn] takes a look at the German Zweikanalton (also known as A2 Stereo) standard, and compares it with the NICAM standard that was used elsewhere in the world.

Zweikanalton is quite simple compared to NICAM (which we covered previously), being purely analog with a second channel transmitted alongside the first. Since it didn’t really make much of a splash outside of the German-speaking countries, equipment for it is more limited. In this video [Matt] looks at the Philips PM 5588 and Rohde & Schwarz 392, analyzing the different modulations for FM, Zweikanalton and NICAM transmissions and the basic operation of the modulator and demodulator equipment.

An interesting aspect of these modulations are the visible sidebands, and the detection of which modulation is used. Ultimately NICAM’s only disadvantage compared to Zweikanalton was the higher cost of the hardware, but with increased technological development single-chip NICAM solutions like the Philips SAA7283 (1995) began to reduce total system cost and by the early 2000s NICAM was a standard feature of TV chipsets, just in time for analog broadcast television to essentially become irrelevant.

Continue reading “A Look At Zweikanalton Stereo Audio And Comparison With NICAM”

How To Make A Larger Air-Cored Inductor

Radio amateurs often have a love-hate relationship with home-made inductors, sharing all kinds of tips and tricks as to how the most stable nanohenry inductor can be wound. But there’s another group in the world of electronics with an interest in high-quality inductors, namely the audio enthusiasts. They need good quality inductors with a values in the millihenries, to use in loudspeaker crossover networks. [Homemade Audio] takes us through their manufacturing process for these coils, and the result is a watchable video resulting in some very well-made components.

The adjustable former is a machined aluminium affair of which we’re treated to the full manufacture. It’s likely the same results could be achieved with a 3D printed reel. The free-as-in-beer Coil64 on Windows is used to calculate the dimensions and number of turns, and it’s set up on a jig with a cordless screwdriver doing the winding. The best technique for flat layers of turns is explained, and a coat of varnish is put on each completed layer. We’re guessing this is to stop the coil “singing” at audio frequencies.

With a set of cable ties holding it together the result is a very tidy component. It’s adjusted a few turns to get the right value with an LCR meter, however experience tells us that a tiny percentage either way won’t harm the resulting network too much. If you make your own speakers, the video below the break could be extremely useful.

Need a loudspeaker primer? We have just the article for you.

Continue reading “How To Make A Larger Air-Cored Inductor”