Restoring A Forgotten Dot-Matrix Printer

Dot matrix printers are the dinosaurs that won’t go extinct. They are not unlike a typewriter with the type bars behind the ink ribbon replaced by a row of metal pins controlled by solenoids, each pin being capable of printing a single pixel. At their best they could deliver a surprising level of quality, but their sound once heard is not forgotten, because it was extremely LOUD.

[Wpqrek] bought an old dot-matrix printer, a Commodore MPS 803. Sadly it didn’t live up to the dot-matrix reputation for reliability in that it didn’t work, some of its pins weren’t moving, so he set to on its repair. Behind each of those pins was a solenoid, and after finding a crack in the flexible ribbon to the head he discovered that some of the solenoids were open-circuit. On dismantling the head it became apparent that the wires had detached themselves from the solenoids, so he very carefully reattached new wires and reassembled the unit. Of course, he had no replacement for the flexible ribbon, so he made a replacement with a bundle of long lengths of flexible hook-up wire. This hangs out of the top of the printer as it follows the carriage, but for now it keeps the device working.

Dot-matrix printers are a favourite for our readership. Among others, we’ve seen another Commodore get the Python treatment, as well as an Apple capable of printing in full colour.

Hackaday Podcast Ep3 – Igloos, Lidar, And The Blinking LED Of RF Hacking

It’s cold outside! So grab a copy of the Hackaday Podcast, and catch up on what you missed this week.

Highlights include a dip into audio processing with sox and FFMPEG, scripting for Gmail, weaving your own carbon fiber tubes, staring into the sharpest color CRT ever, and unlocking the secrets of cheap 433 MHz devices. Plus Elliot talks about his follies in building an igloo while Mike marvels at what’s coming out of passive RFID sensor research.

And what’s that strange noise at the end of the podcast?

Direct Download (59.2 MB MP3)

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Python Resurrects Dot Matrix Printing

These days a printer — especially one at home — is likely to spray ink out of nozzles. It is getting harder to find home laser printers, and earlier printer technologies such as dot matrix are almost gone from people’s homes even if you’ll still see a few printing multipart forms in some offices.

[Thomas Winningham] bought an old Commodore dot matrix printer in a fast food parking lot for $20. How hard could it be to get it working? How hard, indeed. Check out the video below to see the whole adventure. The principle behind the printer is simple enough. The head has one or two rows of pins each controlled by a solenoid. The head moves across the paper and your job — should you decide to accept it — is to make the pins push out at the right spot. An ink ribbon like a typewriter uses — oh yeah, more vanishing tech — leaves ink on the paper where it gets punched by the pin.

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Mini-Banners for Small Occasions

Do you often find yourself needing to make small signs? Perhaps you’re trying to put a notice on the office fridge, but you’re just not in the mood for the usual Comic Sans-on-A4 staple today. A banner of some sort would do the trick, but… a small one, right? [Mike Ingle] has the answer – making mini-banners on old receipt printers.

[Mike] was a fan of Paint Shop in the 1980s, which among other things, enabled the printing of long banners on the popular dot matrix printers of the era. Realising that receipt printers have a similar ability to print on a long continuous strip of paper, he decided to see if it was possible to create small banners using the hardware.

The hack is simple – ImageMagick is used to generate a one-bit black & white bitmap that is then processed with some custom C code to generate something the printer can understand. It’s then a simple matter of hacking up the original RS-232 cable to fit a DB-9 (aka DE-9) connector, and spitting out the instructions over serial.

The mini-banners are cool, and we could imagine having some fun with such a project, using it to print out tweets or putting it into service as a stock ticker. It’s a great example of cleanly interfacing with existing hardware to create something outside of the original design intentions. Such printers are fertile ground for hacks – like this printer that can spit out the US Constitution in 6 seconds flat.