Mysql: the definition of table prevents operation … on table

This is a tricky one affecting MySql table updates which have views. Documentation about this error actually explains the cause, but doesn't connect the dots. I have a view V on table T and want to delete some rows from T. That works fine as long as the DELETE statement doesn't involve the view, so … Continue reading Mysql: the definition of table prevents operation … on table

Ubuntu 20.04 getting wrong IP address

Yesterday (early August 2021) my Ubuntu 20.04 installation started configuring all network interfaces (wifi, ethernet) with IPv4 addresses from the wrong network segment block, namely 192.168.0.x. IPv6 still worked fine. I didn't figure out whether that's due to a change in the router or the OS (I suspect the router, because the situation improved when … Continue reading Ubuntu 20.04 getting wrong IP address

Double push-pull amplifier with cross over compensation

Push-pull amplifiers [1] are great for driving heavy loads because they divide work among two transistors and produce a centred output signal that can freely move up or down around the centre. Simple push-pull amplifier When powering the amplifier with a single power source (eg. a 12V battery), then the output signal oscillates around half … Continue reading Double push-pull amplifier with cross over compensation