- New custom tape reader is based on a minimal optical setup using modern parts
- LED tuning and sensor calibration required a lot of patience during the early testing phases.
- Reducing crosstalk became a key factor in stabilizing signal accuracy consistently
A retro computing enthusiast has built a newly created punched tape reader that relies on a minimal set of modern components called Putapre.
The device comes from Skyriver, which wanted a simple optical system capable of handling punched tape without the complexity of old contact mechanisms.
Its design uses an 8-bit PIC18 microcontroller connected via USB and relies on a phototransistor paired with an infrared LED to detect each hole in the tape with controlled light passing through the paper.
How the optical system was adjusted for precision
Skyriver explains that achieving the right balance of lighting and sensors took considerable time: the LED intensity required repeated adjustments to avoid false triggers, while the phototransistor sensitivity had to be set to detect precise transitions.
The manufacturer also focused on reducing crosstalk between channels, which required several hardware adjustments.
The choice of ribbon material turned out to be important because different papers reacted differently to the passage of light and, after several tries, the system reached a point where the ribbon could pass cleanly with consistent readings.
To stabilize the ribbon, Skyriver created a 3D printed guide that keeps the material aligned with the LED and sensor.
The guide ensured that the tape did not move during movement and allowed the optical path to remain stable throughout the feed.
With this mechanical support installed and some practice handling the settings, the reader became predictable enough for the demonstration.
Skyriver notes that these improvements were essential to achieving reliable hardware performance.
The software responsible for interpreting the signals currently performs only essential operations, but Skyriver promises to improve it in the future.
Early estimates indicate that the reader runs at about fifty bytes per second, meaning users should not expect high data reading speeds.
However, this speed is still faster than older contact systems, but remains modest by any modern standard.
Punched tapes held an important place in early computing before magnetic media replaced them, and they still attract the interest of enthusiasts.
Skyriver hints at designing a compact punching device so that tapes can be produced without using vector files or laser cutters.
That said, the output of this project is quite slow and its purpose is very limited, suggesting that it will have limited practical value.
Still, it reflects the appeal of reconstructing historical technology for experimentation rather than efficiency.
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