this post was submitted on 20 Jan 2025
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1840s, actually. The patent was granted to a Scottish man named Alexander Bain.
First thing's first, the telegraph. An electric circuit which can be energized or not energized at the push of a button called a telegraph key. At the other end is a solenoid which is spring loaded up, and an electromagnet on the circuit pulls down when the line is energized. Originally this was supposed to cut into paper tape to "print" the morse code message, but telegraphers quickly learned how to hear the letters in the clicks, a good telegrapher just...hears words. So they did away with the tape.
Morse code telegraphs require a single circuit to transmit an on/off keying message, the following aparatus uses five:
If I understand this right, the message would be written on non-conductive paper with conductive ink, and then wound around a cylinder that featured a whole bunch of insulated conductive pins, each kind of forming a "pixel." A mechanical probe would check each one of those pins in turn, each pin in a row, and then shifting to the next row at the end. if it was conductive it meant there was ink there so click. So it would perform a raster scan. At the other end was paper that was coated with an electrosensitive material that would darken with the application of current, so at each pixel if the conductive ink on the original completed a circuit, current would be applied at that pixel on the copy, producing a low quality probably unusable copy. It was difficult to get them truly in sync plus it would have been hilariously low resolution. But it did somewhat function.