Paper Tape Reader

Repository: github.com/Supermagnum/paper-tape

Design and documentation by Jürgen Müller / e-basteln. This repository contains the firmware, PCB design files, and manufacturing data for the manual optical paper tape reader described on the e-basteln Paper Tape Reader pages.

Overview

This little manual paper tape reader is easy to build and operate. It connects to any modern computer via USB, and performs well with all kinds of 5 to 8 bit paper tape, including translucent paper materials. To compensate for sensor tolerances and adjust to different paper types, it can automatically calibrate its optical sensors.

You must order 1.6mm thick pcbs!

Note that the main board and included spacer template PCBs use 1.6 mm thickness. The Gerber files in gerbers/papertape_spacer/ are for those 1.6 mm templates (identifiable by their larger aperture holes), used as alignment guides during assembly.

The actual spacers are 2× 1.2 mm thick (total 2.4 mm) and are not the same as the template Gerbers; make them separately. If you fabricate the 1.2 mm spacers as PCBs, order them as a separate job from the 1.6 mm main/template boards. Both 1.6 mm and 1.2 mm are standard thickness options at JLCPCB and PCBWay, with a minimum order of 5 pieces each.

The files for those, 1.2mm thin PCB's are here:

https://github.com/Supermagnum/paper-tape/tree/main/gerbers/papertape_spacer

The material of the spacers is not important, they just have to be light-tight. Options include 3D printing in black filament, or cutting from 1.2 mm black acrylic or similar opaque material. Use the 1.6 mm template PCB as a guide when making them.

Important note!

The aperture hole for the feed track is only 1.2 mm in diameter, matching the feed holes in the paper tape for maximum signal modulation.

On both aperture PCBs this hole needs to be drilled out to 1.8 mm to accommodate the LED and phototransistor, as indicated in the silk screen print on the PCB. But do not drill all the way through; this must be drilled as a blind hole, preserving the 1.2 mm optical aperture!

Note that extreme care must be exercised in drilling this hole. Use a drill press and/or much care to drill to the right depth. The standard tolerance for a 1.6 mm PCB is ±10%, which means ±0.16 mm.

The WP406A10SURDK LED protrudes 1.55 mm up from its body; tolerance is ±0.25 mm, so start with a hole depth of 0.5 mm. Maximum you'd ever need to drill is 1.0 mm, leaving at worst 0.44 mm of wall.

Read more at https://github.com/Supermagnum/paper-tape

BOM: https://github.com/Supermagnum/paper-tape/blob/main/docs/papertape_bom_PCBWay%20Community.csv