It's helpful to step out of the box with those kinds of questions, and consider what it is the sensor is doing. Abstraction is great for programming and reasoni

It's helpful to step out of the box with those kinds of questions, and consider what it is the sensor is doing. Abstraction is great for programming and reasoning about complex objects like cars (have key, insert key press pedal to move, that kind of thing), but if you're going to use something like a sensor in a way that it isn't designed, you have to go lower in your abstraction level and look at, for example, the physics of what it's doing. Often a thing that emits can receive what it outputs (if you measure how the membrane of an ultrasonic sound generator is moving, for example, although you'd also have to add additional components at which point it becomes a ping sensor), but sometimes it's not feasible. I really enjoyed Practical Electronics for Inventors for this kind of perspective.