Week 12 ~ machine week
A toilet paper plotter
Danny and I took on the inkjet cartridge. Jake had drawn our attention to this project and placed an order for the HP6602 printhead and the transistor arrays.
Unfortunately the printhead did not arrive in time, so Danny went out to buy an alternative (HP 61).
The exposed pads looked very different from the hack documented fro the HP6602, but we thought that potentially it might follow a similar logic
(switching individual pads would activate separate nozzles). Using the continuity mode on our lab multimeter, we established common
connections between two of the pads with larger traces going into them, and went with the assumption that this could be GND.
Pads on the flex-circuit of the HP61 cartridge.
Soldered connections to the pads.
Test triggering the inkjet by applying ~18-22 V from a variable power supply.
Transistor arrays wired up, before realising this wasn't going to work ...
http://spritesmods.com/?art=magicbrush&page=3
Too late, but for a longer reverse-engineering job ... the waveforms to control the HP61, documented here
Evidently, the pen won the battle in becoming the toilet-paper plotting tool. In the final early hours push of this project, my main contribution to the project was a sheet of steel carefully hand-rolled in a wood-working vice ...
(my phone died, so no pictures of the process - but see the video above and below for before and after impressions).
Plotter before addition of the steel plate
Plotter after adding steel plate, writing "HTMAA"
The final machine in E14, thanks Shonit for the photo.
Final interface