"The earliest ventilators of the 1950s were primitive devices with…

"The earliest ventilators of the 1950s were primitive devices with even more primitive control and sensor systems, but they worked, and they saved many lives. Some of the early ones were built in workshops. This ventilator has a very primitive and basic design, but then it does benefit from a modern electronic control system. This is a basic ventilator design using materials that would still be readily available (or re-purposed) if a pandemic were to occur. It uses wood, tape, plastic bags, threaded pipe, solenoid valves, security system magnetic switches, and a PLC (Programmable Logic Controller). The prototype shown does not yet incorporate all of the proposed design features and the control program still needs some work to make it more stable and failsafe but it does function, as you can see from the video.

The Pandemic Ventilator Project is an open source hardware project. If you build your own development unit, please share your ideas, and experience at www.panvent.blogspot.com"

https://www.instructables.com/id/The-Pandemic-Ventilator/