测量市电 - AB伪差分:Siglent | Tek
纹波:Tek | Rigol
Micsig/汽修: https://space.bilibili.com/476743057/channel/seriesdetail?sid=862170
Simulation Program
Free: https://en.wikipedia.org/wiki/List_of_free_electronics_circuit_simulators
Micro-cap | Original $4495, now free: http://www.spectrum-soft.com/download/download.shtm