Virtually every electronic component that is available for sale today will have a detailed datasheet that you can reference to find information that part’s operating parameters, tolerances, and so on. Thanks to our practically limitless modern storage and the internet, digital copies of those datasheets are readily-available. But older chips that haven’t been produced in decades tend to lack documentation. Old technical drawings and datasheets were simply never archived in digital formats. CuriousMarc received some important documents for vintage HP parts, but they were on microfiche film. That’s why he built a custom microfiche reader so that he could take a look at that film and archive the documents in a digital format.
Imagine you had a B-size technical drawing in 1975 that was printed on paper. That would be 11 x 17 inches and, when combined with stacks of other drawings, you’d end up with filing cabinets full of drawings. Digital storage, especially for drawings, was still very expensive so you might take a photo of the drawing that is smaller than the B-size paper. But even those photos take up a lot of storage space so then you make those photos really, really tiny. That is the idea behind microfiche film, which was used for archiving all kinds of documents in the past. Because the film is too small to see unaided, microfiche readers were commonplace in offices and libraries. Unfortunately, microfiche readers are uncommon today. They’re also bulky enough that even dedicated geeks have a hard time justifying keeping one around.
CuriousMarc thought that his microfiche film could contain cross-reference lists for old HP parts, which would be very useful for those working on vintage electronics, instruments, and retro computers. He didn’t want to buy a big old microfiche reader and so he built a far more compact version using modern parts. The two most important components of this build are a cheap digital microscope and an LCD backlight. The backlight is the right size for the film and shines through it to give the documents contrast. The microscope zooms in on the itty bitty documents and makes them clearly visible. This digital microscope can snap photos of whatever it is pointed at. By zooming in all the way and capturing many photos of the documents, high-resolution digital copies can be stitched together. It can also be used as a simple microfiche film viewer. Even if you don’t care about old part datasheets, a similar setup could be used for other research, such as for reading historical newspaper articles that have been stored on microfiche film.