Award clock put to good use as a bench meter

award-clock-turned-voltage-meter

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.

[Read more...]

Breathing life into an old LCD

panel

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

myvu-led-module-teardown

[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?

[Read more...]

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!

[Read more...]

Driving an LCD character display using custom HID codes

Here’s an external display meant to help you keep track of your computer’s status. It connects via USB and is driven by a PIC microcontroller. It listens for a small set of commands, using those to implement a simple control protocol to drive the screen.

[Andrew Gehringer] designed the device around a PIC 18F2550, which offers native USB control. He’s using Microchip’s USB stack to enumerate the module as an HID device. It listens for commands 0x10 through 0x23. These clear the display, write strings to each of the four lines of the display, and switch the LCD backlight. Of course the project includes a program [Andrew] wrote to feed the display. It  has a GUI which let’s him decide what information is displayed and how it is formatted. This helper app hangs out in the system tray for easy access.

Reverse engineering Solari soft flap displays

This is a side view of the guts of a one character Solari soft flap module. This is the type of mechanical display used in some transportation hubs that have a flap for each letter. The motor turns the flaps through the alphabet until it gets to the target letter. Recently [Boz] had a client approach him who needed a custom controller for a 20-character soft flap display.

The process started out with a magnifying glass and multimeter which yielded a rather complicated hand-drawn schematic. An optical encoder is used to judge which character is currently displayed. After analyzing the output using an oscilloscope [Boz] designed a PIC based driver board which is controlling the display seen in the clip after the break.

The great thing about these displays is that they don’t use any electricity except when they change letters. This sounds like the predecessor of ePaper and makes us wonder if there are any companies developing high-contrast ePaper to replace soft-flap digits?

[Read more...]