A while back, I came across a set of high-quality photos taken at the former Electro Vox factory in Montréal in 1979. The photos show fire alarm system components being assembled by hand and products being demonstrated. It’s unusual to find pictures of fire alarm equipment being assembled (especially older equipment)—I find it fascinating to get a glimpse of how the process worked.
Products similar to the ones shown in these photos are discussed in this thread, which pertains to old Cerberus Pyrotronics voice systems.