When [Neelandan]‘s cheap flashlight’s internal rechargeable battery died, he scrounged for a replacement. Ultimately, the brightness of the light suffered with his new battery, taken from an old cell phone since he had dropped the voltage a bit. Upon inspection he saw that he would have to swap the individual resistors for each lamp to get the desired brightness again. This wasn’t really acceptable as he would have to repeat the process if he used another re-purposed battery with different specs. Instead, he added a new circuit to supply constant brightness until the voltage drops below 2.7 volts. We love to see hardware resurrected, even if it is just a cheap LED flashlight.