I learnt

something new today: resistors now have numeric codes and so I don't to struggle to remember what brown/cream/blue means. A student proposed a mobile app to do optical character recognition, which sounds a lot harder than just understanding the tiny SMD codes. The resistors are about 1mm wide. 15 times 10 to the power 3, or 15 kilohms, if I understand the system. More fun with the macro tubes.