A Flashlight Schematic
Well, I took the broken flashlight to work. I have colleagues there who are genius electrical engineers and one in particular, Sam, had a fun time with this challenge. I explained to him the situation and handed him the circuit board. He peered closely at the board, rotating it round and round as he traced all the connections. As he did so he made notes on my whiteboard and after a few minutes he had deciphered the full schematic of the circuit and it's intended operation. We then hooked up a bench power supply and took some measurements (with a much nicer multimeter than I have at home). We measured 2.45 mA of current flowing when 6V is connected and the lights are off. At 220 mA hours of battery life: 220/2.45 = 89.79 hours 89.79 hours / 24 hours/day = 3.74 days Which totally correlates with my experimental data. Here's the schematic for your viewing pleasure (click to make it bigger): You can see some measurements we took and a curve for the diodes. Yes, ...