Helping out a friend with a picture or two of the Astec UM1233 RF Modulator’s inner workings. If you’re curious, it’s a device which was incredibly popular in the 80s and 90s in home computers, and takes video and audio as an input and turns them into either VHF or UHF (depending on country) radiofrequency signals – the same signals as analogue TV tuners expect to receive. If you crack open a ZX80, ZX81, Spectrum of almost any model, Commodore 64, ORIC, Newbrain, Dragon – almost any 80s microcomputer aimed at the home market – you’ll probably find one of these.