Few people have heard of it, yet many consider John Blankenbaker's KENBAK-1 to be the first commercial personal computer.
DIY $33 Oscilloscope Kit
By James Grahame
I know it's not Retro, but you can certainly use this clever DIY oscilloscope kit to repair vintage gadgetry. It has a maximum analog bandwidth of 1MHz with 8 bit resolution, includes auto, normal and single trigger modes, adjustable vertical position, frequency counter, and a built-in 500Hz/5Vpp test signal.
It runs on 9-12VDC and weighs in at a featherweight 70 grams. The big downside is that there's no case, but I'm OK storing it in a cardboard box when not in use. The kit requires surface mount soldering, but you can also buy the little beast fully assembled in the USA for only $49.
