My favorite thought experiment is building telephone and radio in Ancient Egypt, sometime ~1000 BC.
Silver / zinc batteries can work an acetic acid, easily distillable from vinegar. With some luck, alkaline batteries are also doable (IDK if Egypt had any sources of manganese). With some effort, sulfuric acid can be produced, allowing lead-based batteries. Two of the three are rechargeable, but having the acid and zinc as consumables is also OK.
Copper wire is perfectly doable; copper was produced in mass quantities, drawing it through a ceramic die should do the trick. Producing cheaper brass (copper + zinc) is also not a problem.
For magnets, we'll need some iron. It can either be produced from ore, or taken (as an alloy with nickel) from meteorites that Egyptians also found. We don't need much.
Insulation can be made from canvas and oil (like oil painting, but without the picture). Wood can be the non-conducting construction material instead of plastic.
With this, we can easily build telegraph and telephone. With some high-voltage coils, we can build a radio transmitter capable of Morse code transmission. This all would look like pure magic and would have immense military value.
Note that it would take nothing extraordinary technologically: most things are readily available, no need to build machines to build machines, etc. It would only take a much larger body of knowledge about the world.
Silver / zinc batteries can work an acetic acid, easily distillable from vinegar. With some luck, alkaline batteries are also doable (IDK if Egypt had any sources of manganese). With some effort, sulfuric acid can be produced, allowing lead-based batteries. Two of the three are rechargeable, but having the acid and zinc as consumables is also OK.
Copper wire is perfectly doable; copper was produced in mass quantities, drawing it through a ceramic die should do the trick. Producing cheaper brass (copper + zinc) is also not a problem.
For magnets, we'll need some iron. It can either be produced from ore, or taken (as an alloy with nickel) from meteorites that Egyptians also found. We don't need much.
Insulation can be made from canvas and oil (like oil painting, but without the picture). Wood can be the non-conducting construction material instead of plastic.
With this, we can easily build telegraph and telephone. With some high-voltage coils, we can build a radio transmitter capable of Morse code transmission. This all would look like pure magic and would have immense military value.
Note that it would take nothing extraordinary technologically: most things are readily available, no need to build machines to build machines, etc. It would only take a much larger body of knowledge about the world.