If I were to take a standard AC to DC converter, say a laptop charger, and hook up the input side (which expects 120VAC at 60Hz) to a DC power supply of some sorts, will the electricity still be “converted,” or will it just not work at all? I am clearly very uneducated when it comes to electronics (albeit working on it) so I would very much an ELI5 answer Thanks!
It depends on the design of the power brick, but not something to try due to hazard, at the least could fry the adapter or at worst cause an electrical fire. There would be no reason other than, “here, hold my beer.”
Some laptop adapters may use a bridge rectifier followed by a buck converter, but there’s still plenty that use a transformer to step down AC voltage before presenting it to the rectifier-regulator. A transformer will become a toaster if DC voltage of any appreciable level is applied.
If the adapter happens to be one that does not use a transformer, a high enough DC voltage has to be applied with correct polarity. The voltage required would be output voltage plus “dropout” voltage of the buck converter. Dropout voltage could be pretty high so it can get into dangerous levels. If you managed it without electrocuting yourself or burning down your house, it could possibly output properly regulated voltage.
In reality, a practical application for DC-DC conversion is adapters for cigarette lighter sockets. I actually have one of those for my laptop. It steps up 12V DC from a cig lighter socket to the 19V DC plug for my laptop using something called a boost converter. USB cig lighter adapters are common and typically use a buck converter to step down 12V to the 5V of a USB plug.