it doesn't. it only works incidentally. The author isn't an EE and has designed a circuit as if an artist (or an AI) drew a picture of what a circuit looks like.
The weird topology voltage divider attenuates the signal. the op-amps buffer the output. The 470R resistors do nothing. The 1k/1k virtual ground does nothing.
The rest of the authors writings smell of /r/iamverysmart
once, when complaining to a colleague about our workplace and their hiring and staffing idiosyncrasies, I quipped "I should give <manager> a copy of TMMM". My colleague, without missing a beat said "You should give him two copies so he can read it faster"
I thought about making one of these - actually I designed it, but never made the PCB for it - because the internet is full of similar ones:
https://www.ebay.com.au/itm/195143066807
There are a few dynamic pricing energy retailers in Australia too. It often goes negative, sometimes for many hours at a time. Usually it’s hard to make money off it because it’s often at times of the year and day that there is no need for heat/cooling.
it's actually persisted more recently. I just checked a High Sierra machine. "Messages" has an "Add Jabber Account" menu option. An it's recent enough that it plays nice with all my existing more modern iPhone/macOS etc iCloud messages.
In the slightly olden days, iMessage - or whatever it was called then - had a built in jabber client, and there was brief period (Sierra era?) that iMessage/iCloud could sync up all your messages across google and apple and SMS.
I _think_ it would have enabled this functionality, if anyone knew and/or investigated it.
I have once of his Klein bottles. It came in the most amazing personally decorated package that I've kept that too, and value it almost as highly as the glassware.
I have a HP laserjet 6L from 1993. It still works, although the paper feed needs to be encouraged sometimes. Doesn't get a lot of use anymore, but I think we only ever bought one new toner cartridge for it.