One transistor to help them all
I grabbed a KC508 - a general-purpose NPN transistor common in Czech and Slovak electronics, the local equivalent of a BC547 - and wired up a simple signal inverter on a breadboard.
Jan Rydval
IR Deep(er)dive
Now I have a working CL9 Core Universal Remote and an oscilloscope.
Chamaleon Ultra RFID
I came across the Chameleon Ultra - a tiny device capable of reading, cracking, writing, and emulating LF and HF RFID identification cards.
Oscilloscope to every home
I decided on the Rigol MHO984. It offers 4 channels, a logic analyzer, wider bandwidth, Wi-Fi, Bluetooth, Ethernet, and remote control capabilities.
CL9 Core Universal Remote
This remote is special because of the way it was designed. And it is more geekish than HP-41CX today. It uses a 6502 processor and 32 KB of static RAM together with a 4-bit processor serving the keyboard, display, and real-time clock.