Printing Text with a Chart Recorder

A chart recorder printing 'Hello World'

Chart recorders are vintage devices that were used to plot analog values on paper. They’re similar to old seismometers which plot seismic waves from earthquakes. The device has a heated pen which moves across a piece of thermally sensitive paper. This paper is fed through the machine at a specified rate, which gives two dimensions of plotting.

[Marv] ended up getting a couple of discontinued chart recorders and figured out the interface. Five parallel signals control the feed rate of the paper, and an analog voltage controls the pen location. The next logical step was to hook up an Arduino to control the plotter.

However, once the device could plot analog values, [Marv] quickly looked for a new challenge. He wanted to write characters and bitmaps using the device, but this would require non-continuous lines. By adding a solenoid to lift the pen, he built a chart recorder printer.

After the break, check out a video of the chart recorder doing something it was never intended to do. If you happen to have one of these chart recorders, [Marv] included all of the code in his writeup to help you build your own.

[Read more...]

Red Bull Creation: A Giant Daisy Wheel Printer

While most of the teams in this year’s Red Bull Creation didn’t really pay attention to the theme of ‘reinventing the wheel’, 1.21 Jiggawatts did. Their creation, a giant typewriter that can be suspended along the side of a building, takes its inspiration directly from 1970s typewriters and printers. Yes, it’s a giant daisy wheel typewriter.

The basic idea of a daisy wheel typewriter is a wheel with a few dozen petals, on the end of which is a single letter. To print a letter, the wheel spins around, and a solenoid mechanism strikes the letter against a piece of paper. This was cutting edge tech in the 70s, and was a fast (and cheap) way for computers to print out letter-quality reports.

1.21 Jiggawatts used a ladder as the rail to move down a line of text. The movement from line to line was supposed to be done by dangling the ladder off a chain with a few sprockets attached to motors. Unfortunately, the team couldn’t quite get the machine working for the competition and live event, but the build does show an amazing amount of creativity and respect for classic, forgotten technology.


Learning to Reverse Engineer on a Broken Printer

Lexmark Hack

When a Lexmark inkjet printer stopped working, [Mojobobo] was able to claim it as his own. He quickly realized that the machine was flooded with ink and not worth repairing, but that didn’t mean he couldn’t still find a use for it. When he learned that the printer’s firmware was not only upgradable but also unprotected, he knew he should be able to get the printer to do his own bidding.

[Mojobobo] started his journey with the motherboard. The unit still powered up, but it was asking to insert a “duplex module” before it would boot any further. [Mojobobo] first tried to find a way to trick the duplex module sensor, but was unsuccessful. His next step was to search for some kind of serial communications port. He didn’t have an oscilloscope, so instead he used a speaker with a wire probe. In theory, if the wire was pressed against an active serial port, he would be able to hear varying tones through the speaker. Sure enough, he found some interesting tones after probing around some ports next to a “JTAG” label. He looked up some information about the nearby chip and found that it included an SPI bus.

After some internet research, [Mojobobo] learned enough about SPI to have a rough idea of how to use it. Having limited tools available to him, he decided to use his Arduino to try to communicate with the motherboard. After wiring up a simple circuit, (and then re-wiring it) he was able to dump the first 4096 bytes of the motherboard’s boot loader to the Arduino via the SPI interface.

[Mojobobo's] next steps will be to find a faster way to dump the boot loader. At 9600 baud, he grew tired of waiting after three hours. Once he has the full boot loader he intends to search for a way to bypass the duplex sensor and get the board to finish booting. Then he may just use the printer for its scanning functions, or he might find other interesting uses for it.

Old Inkjet Turned Into An SVG Plotter


What do you do when you have an old printer, a portable CD player, and a handful of other electronics sitting around? Turn it into a plotter, of course.

The frame of the plotter was taken from a ye olde Epson printer, reusing the two stepper motors to move the paper along its length and width. The pen is attached to the laser head of a junked portable CD player. With this, it’s just three stepper motors that allow the Arduino control system to move the pen across the paper and put a few markings down.

The motors on the printer are, in the spirit of reuse, still connected to the printer’s driver board, with a few leads going directly from the Arduino to the parallel port interface. The motor in the CD player is another ordeal, with a single H-bridge controlling the lifting of the pen.

On the software side of things, a Processing sketch reads an SVG file and generates a list of coordinates along a path. The precision of the coordinates is set as a variable, but from the video of the plotter below, this plotter has at least as much resolution as the tip of the pen.

[Read more...]

Examining Vintage Printer Server Hardward for Apple II


Need to share a printer between several Apple II computers? Of course you don’t, but back in the day this would have been a really awesome piece of hardware to own. It’s a Pacemark iiEasy Print (we’re not sure on the capitalization of the name so talk amongst yourselves). It is an automatic buffer and switch that you can have now-a-days for just a couple of Hamiltons. [David] doesn’t mention where he “acquired” his specimen, but all the details about his adventures reverse engineering the card are shared in detail.

First off, we have to mention his unorthodox bench tools. To the untrained eye it would appear that he has attached the iiEasy Print to a Commodore 64; and that eye would be right. [David] says he uses the C64 something like an Arduino (if that’s even possible). The green card is plugged into the C64 memory bus, connecting to the DIP socket breakout board on the left and the chip select pins for most of the other IC’s on the original board. The gist of this setup is that it’s simple to use the “passthrough” DIP socket to monitor what the 6502-like processor is doing, while mapping the memory with the help of the chip select signals.

What did he learn from all this? Quite a lot but you might as well click that link above and hear it from his own mouth.

Microcontroller enumerates as USB printer — can be programmed by printing


This is a fascinating concept. We’re not sure of its usefulness, but it definitely stands on its own just for the concept. [Dean Camera] just added a new HID class to the LUFA project that lets you flash AVR chips by printing to them. This means once you have a file like the one seen open in Notepad above, you can just click on File, then on Print, and the firmware will be uploaded to the chip.

[Dean] is the creator of the LUFA project and still likes to get his hands dirty hacking around with it. This idea came to him while he was exploring the concept of using the MIDI protocol to program a chip. That didn’t pan out because of the way Microsoft has handled MIDI in newer versions of Windows. But he did get the idea of making LUFA identify itself as a simple USB printer. He dug into the specification and figured out how to do that. Once Windows connects to the device it doesn’t really care what data gets sent to it. So [Dean] wrote a parser for the bootloader which could accept the incoming hex code and write it to the chip’s program memory.

Everything you need to know to make a Laser engraver from scrap


Check out the Einstein head which [Sebastian Müller] etched on the cover of his calculator using a laser engraver he made from scratch. We think he did a great job with the build, but we’re even more impressed with the work he put into sharing the techniques he used to salvage and repurpose all the components. It’s a perfect resource that should be pretty easy to adapt to different model/manufacturer source hardware.

He used an old scanner and an old printer for the bulk of the parts. These both originally included stepper-motor actuated gantries, which pull together to form the x and y axes in his Frankenstein Laser Engraver. As the parts came together he started in on the control electronics which include a couple of EasyDriver stepper motor boards and an Arduino.

At this point he took the machine for a test-run, attaching a marker to the carriage to use it as a pen plotter. After putting in a solid performance at this [Sebastian] moved on to adding in the laser diode. He covers how to drive the diode, as well as focal point alignment in great detail. It seems like his webpage post has the same content as the Instructable linked above but we wanted to leave the link just in case.