Small portable FM PLL radio with clock and alarm - RP 5201 PLL. Retail price: ~$25-$30.
2 R6 cells for clock / station memory backup (optional), 4 R14 cells or 230V AC for full operation.
Decent speaker.
Two keyboard boards connected with single wire pair each - reading keys by measuring resistance.
This one is incomplete - transformer is missing, otherwise it works fine. Mains socket is couples with mechanical switch disabling internal battery.
Power supply filtering is very impressive for this class of products - there are 3 coils, 2200uF + 1000uF + 2 x 470uF + 6x 220uF + 100uF (one of these might be DC decoupling for speaker actually).
Audio amplifier: "CHMC S75"/"D820"
Microcontroller: TMP86FM29LUG. Toshiba, 8-bit TLCS-870/C series, 32kB FLASH, 1.5kB RAM, 10bit x 8ch ADC, built-in LCD driver, dual clock. Supply current 4.5mA typ, 8-20uA in SLOW/SLEEP modes. UART bootloader.
Coils on small board resembling hybrid circuit.
Radio chip.
Both reception and audio quality is pretty decent.
It's worth noting that apart from 2xAA clock/station backup it seems to retain memory with energy from capacitors for a minute or so.
NiMH cells (1.2V) seems to work fine, so semi-discharged primary cells would work also. Consumed current = 6uA.
