Train Surgery I took a hilariously loud, 4xAA-hungry toy train and gave it a proper glow-up: dropped an 18650 in the coal car, used a charger/protect/boost board dialed to ~5.5 V, and added a simple series pot as a volume knob. After some careful teardown, polarity sanity checks (center positive!), and an irresponsible amount of hot glue, it’s now rechargeable and actually pleasant to listen to. The motor clatter is the only thing the volume knob can’t tame—but the wheels go round and round, and I’m calling that a win. 07 January 2026