Fabricating custom displays for a commercial coffee roaster

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Roasting the perfect coffee bean is an art form. But even the most talented of roasters can use a little feedback on what’s going on with their equipment. [Ludzinc] recently helped out a friend of his by building this set of 7-segment displays to show what’s happening with this coffee roaster.

The yellow modules hiding underneath the display panel are responsible for setting the speed of the hot air blower and the rate at which the drum turns. They’re adjustable using some trimpots, but it sounds like the stock machine doesn’t give any type of speed feedback other than direct observation.

The solution was to patch into those speed controllers using the ADC of a PIC chip. They each output 0-10V, which [Ludzinc] measures via a voltage divider. After the speed is quantified the microcontroller outputs to one of the displays. Since there’s a different chip for each readout, the firmware can be custom tuned to suit the operator’s needs.

Keep this in mind if you’re still planning to build that coffee roaster out of a washing machine.

Your own head-mounted display for under two bills

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[D S] wanted his own head-mounted display. What you see here is just his mockup, but somewhere along the way he realized it’s closer to a finished build than just being a stating point. Not only does it work well for gaming, it came in at under $200 all in. You think your girlfriend makes fun of you now for wearing that big microphone headset while playing? Just wait until she gets a load of these!

We’ve embedded an image gallery after the break as well as the description he sent us with his email. The display itself is a 7″ LCD module from eBay that boasts a hair better than 720P resolution: 1280×800. He’s using a pair of ski goggles to strap the display to his noggin. The enclosure is made out of foam board which should help keep the weight down. Inside there’s a Fresnel lens but after reading his description of how he measured the focal length we’re still not 100% clear on how he figured out where to mount it.

Though it may be missing the 3d of the rift,a quick mod could fix that and he’ll be well on his way through the journey to building his own Holodeck.

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Award clock put to good use as a bench meter

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The motivation industry turns out these type of award trinkets by the millions. Here’s a way to actually put the thing to use. Instead of displaying time, the clock dial serves as the readout of a voltage meter.

When we first saw this post we assumed that the hack used some type of coil injection to drive the hands. But it turns out that this is mechanically driven. The image above shows the stepper motor which is mounted behind the clock. Its drive shaft is coupled with the adjustment knob on the back of the clock. The precision of the motor lets the PICAXE set the clock dial based on the number of motor steps. The hour hand shows the tens value with the minutes serving as ones (base 10, not base 60). This means the top measurable voltage is 12V — when the hour hand is at 12 the measurement is 0 volts plus tenths of a volt from the minute hand. With the dial taken care of the rest of the project focuses on measuring the voltage using the ADC, which has an upper limit of just 5V. This is overcome with a simple voltage divider.

After the break you can see the accuracy of the rig as it performs measurements next to a digital voltmeter.

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Breathing life into an old LCD

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Out of the depths of a junk drawer, [Alex]‘s friend pulled out an old monochrome LCD display. This is an older low-resolution display from ancient electronics that unfortunately doesn’t have its own controller chip. No worries, though, because with the help of an FPGA [Alex] figured out how to drive this display.

On the back of this display are eight Hitachi LCD drivers, six column shifters and two row shifters, allowing the LCD to display a 256×128 pixel image. Without an LCD controller, though, [Alex] couldn’t just send a static image to the LCD. Instead, he had to continuously refresh the display just like a VGA monitor.

With the help of a 1500-page PDF titled Hitachi LCD Controller/Driver LSI Data Book, [Alex] was able to dump pixels into the ICs on the display with the help of a Papilio One FPGA board. A lot of work just to display the beautiful [Lena], but she wouldn’t have it any other way.

Pulling the LCD screens out of a MyVu glasses display

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[John Floren] really sells us on a pair of MyVu 301 Video Glasses. He lists the features as being bulky, ugly, and uncomfortable. That’s the reason why he’s showing you how to crack open the glasses in order to steal the tiny LCD modules.

The LCD screen for each eye is mounted inside of the assembly seen above. The screen is perpendicular to the wearer’s eye, with some space in the body to facilitate the lens and reflector that enlarge the image and direct it toward the eye. After removing the display from the module [John] tried to hook it up to a camera via the driver hardware which comes with the glasses. It must have been a bit of a head scratcher that all he could get was a plain white image. This is fixed by finding the polarizing filter inside the module and laying it over the screen. This is demonstrated in the clip after the break.

We don’t know where he’s planning to go from here, but we can suggest a few different projects. This hardware could be useful in creating his own augmented reality hat. Using it as a video game controller is another thing that pops to mind. Wouldn’t it be cool to have this in the scope sight of a light gun?

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Demystifying camcorder CRT viewfinders

Every smartphone (and most dumb phones) has a video camera built into it these days. Some of them are even capable of recording respectable HD video. So we’d bet that the decades old camcorder you’ve got kicking around isn’t getting any use at all anymore. [John] wants to encourage you to hack that hardware. He published a post showing just how easy it is to salvage and use a camcorder CRT.

The gist is that you simply need to hook up power and feed it video. The board that is attached to the CRT has its own voltage hardware to drive the tube. He demonstrates a 9V battery as a power supply, but also mentions that it should be pretty easy to power the thing from a USB port. As for video, all it takes is a composite signal. Of course you’ve got to determine the pinout for your particular CRT module. The method he chose was to use a continuity tester to find the path from a capacitor’s negative leg to the appropriate pin header. Next he used a bench supply to inject a current-limited low voltage until he saw response when probing the pins. Finding the composite-in is a similar trial and error process.

So what can you use this for? Why not make it the display for a simple video game?

Laser charged glowing display

Here’s one of the best takes on a glowing display that we’ve ever seen. Currently [H] is using his creation as a fuzzy clock, but it is certainly capable of displaying just about any messages.

The project uses a wheel of luminous paper as the display surface. This has a glow-in-the-dark quality to it which can be charged up using a bright light source. In this case a UV laser diode was used. This is perhaps the best possible source as its intensity will allow for very quick charging. The innovation here is the use of a second disk as a stencil. Look closely in the image above and you will see that the laser diode is mounted perpendicular to the display surface itself. A mirror reflects — and we believe slightly spreads — the laser dot. It then passes through a cut-out on the black wheel which is shaped as the desired character. As you can see in the video after the break, this results in a crisp and clear glowing letter.

Compare this project to the one that moves the diode itself like a plotter and we think you’ll agree this is a simpler implementation which still looks great!

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