In this video I test a Chinese 12V "2A" switching power supply designed for LEDs, CCTV, routers, etc. It cost me only $ 1.80 including shipping. The actual current capability is about 0.5A and the safety is quite questionable. It's a classic 2-transistor switching power supply with an optocoupler, but it's quite underrated, has poor mains isolation and misses basic safety features like a fuse. It may be dangerous and it can only supply 1/4 of its rated current.