Pushing Pixels To A Display With VGA Without A PC

[Ben Eater] is back with the second part of his video series on building a simple video card that can output 200×600 pixels to a display with nothing but a VGA connection, a handful of 74-logic chips and a 10 MHz crystal. In this installment we see how he uses nothing but an EEPROM and a handful of resistors to get an image onto the screen.

The interesting part is in how the image data is encoded into the EEPROM, since it has to be addressable by the same timing circuit as what is being used for the horizontal and vertical timing. By selecting the relevant inputs that’d make a valid address, and by doubling the size of each pixel a few times, a 100 x 75 pixel image can be encoded into the EEPROM and directly addressed using this timing circuit.

The output from the EEPROM itself not fed directly into the monitor, as the VGA interface expects a 0 V to 0.7 V signal on each RGB pin, indicating the brightness. To get more than three colors out of this setup, [Ben] builds up a simple 2-bit DAC that allows for two bits per channel, meaning four brightness levels per color channel or 64 colors effectively.

See the video after the link for the full details. While pretty close to perfect, a small issue remains at the end in the forms of black vertical lines. These are caused by a timing issue in the circuit, with comments on the YouTube video suggesting various other potential fixes. Have you breadboarded your own version yet to debug this issue before [Ben]’s next video comes out?
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A Lot Of Volts For Not A Lot

There was a time when high voltage in electronic devices was commonplace, and projects driving some form of vacuum or ionisation tube simply had to make use of a mains transformer from a handy tube radio or similar. In 2019 we don’t often have the need for more than a few volts, so when a Geiger–Müller tube needs a bit of juice, we’re stumped. [David Christensen] approached this problem by creating his own inverter, which can produce up to 1 kV from a 12 V supply.

Instead of opting for a flyback supply he’s taken a traditional step-up approach, winding his own transformer on a ferrite core. It has a centre-tapped primary which he drives in push-pull with a couple of MOSFETS, and on its secondary is a voltage multiplier chain. The MOSFETs take their drive at between 25 kHz and 50 kHz from a 555 timer circuit, and there is no feedback circuit.

It’s fair to say that this is a somewhat hair-raising circuit, particularly as he claims that it is capable of delivering that 1 kV at 20 W. It’s usual for high-voltage supplies driving very high impedance loads to incorporate a set of high-value resistors on their outputs to increase their internal impedance such that their danger is reduced. We’d thus exercise extreme care around this device, though we can see a lot of value in his description of the transformer winding.

We can’t criticise this circuit too much though, because some of us have been known to produce far hackier high voltage PSUs.

Exquisite Craftsmanship Elevate Vic’s Creations Above The Rest

This booth was easy to miss at Maker Faire Bay Area 2019 amidst tall professional conference signage erected by adjacent exhibitors. It showcased the work of [Dr. Victor Chaney] who enjoys his day job as a dentist and thus feels no desire to commercialize his inventions — he’s building fun projects for the sake of personal enjoyment which he simply calls Vic’s Creations. Each project is built to his own standards, which are evidently quite high judging by the perfect glossy finish on every custom wood enclosure.

Some of these creations were aligned with his musical interests. The Backpacking Banjo was built around a (well cleaned) cat food can to satisfy the desire for a lightweight instrument he can take camping. His Musical Laser Rainbow Machine (fully documented in Nuts & Volts) was created so little bands formed by independent artists like himself can have a visual light show to go with their live performances. The Music Kaleidoscope is another execution along similar lines, with an LED array whose colors are dictated by music. Venturing outside the world of music, we see a magnetically levitated Castle In The Clouds which also receives power wirelessly to illuminate LEDs

The largest and most complex work on display is an epic electromechanical masterpiece. Par One is a rolling ball sculpture featuring the most convoluted golf course ever. Several more rolling ball sculptures (also called marble machines or marble runs) are on display at Dr. Chaney’s office which must make it the coolest dentist’s lobby ever. The lifelike motions he was able to get from the automatons he built into the sculpture are breathtaking, as you can see below.

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Who Knew Cut Grass Would Be So Tricky To Move!

Like all publications, here at Hackaday we are besieged by corporate public relations people touting press releases. So-and-so inc. have a new product, isn’t it exciting! But we know you, our readers, we know you like hacks, and with the best will in the world, the vast majority of such things have nothing of the hack about them. Just occasionally though a corporate offering does contain a hack, and today we have a fascinating one from Charm Industrial, who are doing their best to make hydrogen from biomass. They were finding cut grass to be an extremely difficult material to handle, and their account of how they managed to feed it from a hopper into their machinery makes for interesting reading.

You might expect grass to flow from a conical hopper like an ungainly liquid, but in fact it readily clogs and forms bridges, blocking the outlet. Changing the design of the hopper made little difference, so they tried an auger. The auger simply compressed the blockage harder, resulting in the counter-intuitive strategy of running the auger in reverse. But even that didn’t work, leaving the area round the auger clear but the rest of the grass as a solid clump. Rotating plows were tried with multiple different profiles followed, but finally they settled upon a vibrating bin activator. It’s a crash course in materials handling, and though the Hackaday bench is likely to avoid having to handle cut grass except when emptying the lawnmower, it’s still worth a look.

We may have done very little with handling cut grass, but we’ve certainly taken a look at creating it.

Look Ma, No Glue! Electrostatic Adhesion As If By Magic

One of the projects at the recent Hacker Hotel hacker camp in the Netherlands appeared to have achieved the impossible. A vertical PCB surface was holding pieces of paper as though they were pinned to it as on a notice board, yet there was no adhesive or fixings in sight. Was Harry Potter among the attendees, ready with a crafty bit of magic at a waggle of a wizard’s wand, or was a clever hack at work?

Of course, it was the latter, as [Jan-Henrik Hemsing], had created an electrostatic adhesion plate because he was curious about the phenomenon. A PCB with extra insulation has an array of conductors on one side that carry a very high voltage. High enough for electrostatic attraction to secure a piece of paper to the PCB.

The voltage is generated from an AC source by a Cockroft-Walton multiplier on the back of the PCB, and the front is coated with Plasti-Dip for insulation. It seems that soldermask is not a reliable insulator at such high voltages.

Using the board, [Jan] was able to attach a piece of paper to it with a shearing force of 5mN at 3kV applied voltage, which may not sound like much but appeared to be just enough to carefully pick the contraption up by the piece of paper. The boards are designed for tessellation, so larger arrays could easily be assembled.

We’ve never had a project quite like this one, but we have brought you an electrostatic ping-pong ball accelerator.

Talk To Your ‘Scope, And It Will Obey

An oscilloscope is a device that many of us use, and which we often have to use while our hands are occupied with test probes or other tools. [James Wilson] has solved the problem of how to control his ‘scope no-handed, by connecting it to a Raspberry Pi 3 running the snips.ai voice assistant. This is an interesting piece of software that runs natively upon the device in contrast to the cloud service provided by the likes of Alexa or Google Assistant.

The ‘scope in question is a Keysight 1000-X that can be seen in the video below the break, but looking at the Python code we could imagine the same technique being brought to other instruments such as the Rigol 1054z we looked at controlling via USB a year or two ago. The use of the snips.ai software provides a pointer to how voice-controlled projects in our community might evolve beyond the cloud services, interestingly though they do not make a big thing of it their software appears to be open-source.

Oscilloscopes do not have to be remotely controlled by voice alone. It seems to be a common desire to take measurements no-handed — one project we’ve featured in the past did the job with a foot switch.

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Building A Simple Python API For Internet Of Things Gadgets

It’s no secret that I rather enjoy connecting things to the Internet for fun and profit. One of the tricks I’ve learned along the way is to spin up simple APIs that can be used when prototyping a project. It’s easy to do, and simple to understand so I’m happy to share what has worked for me, using Web2Py as the example (with guest appearances from ESP8266 and NodeMCU).

Barring the times I’m just being silly, there are two reasons I might do this. Most commonly I’ll need to collect data from a device, typically to be stored for later analysis but occasionally to trigger some action on a server in the cloud. Less commonly, I’ll need a device to change its behavior based on instructions received via the Internet.

Etherscan is an example of an API that saves me a lot of work, letting me pull data from Ethereum using a variety of devices.

In the former case, my first option has always been to use IoT frameworks like Thingsboard or Ubidots to receive and display data. They have the advantage of being easy to use, and have rich features. They can even react to data and send instruction back to devices. In the latter case, I usually find myself using an application programming interface (API) – some service open on the Internet that my device can easily request data from, for example the weather, blockchain transactions, or new email notifications.

Occasionally, I end up with a type of data that requires processing or is not well structured for storage on these services, or else I need a device to request data that is private or that no one is presently offering. Most commonly, I need to change some parameter in a few connected devices without the trouble of finding them, opening all the cases, and reprogramming them all.

At these times it’s useful to be able to build simple, short-lived services that fill in these gaps during prototyping. Far from being a secure or consumer-ready product, we just need something we can try out to see if an idea is worth developing further. There are many valid ways to do this, but my first choice is Web2Py, a relatively easy to use open-source framework for developing web applications in Python. It supports both Python 2.7 and 3.0, although we’ll be using Python 3 today.

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