AV multiband VLF receiver

[WM6]

Dear LRL enthusiast,

here you are an Audio-Visual Multiband VLF receiver as new toy for New Year.

You get visual signal over 4 different coloured LED's and audio signal generated by help of an melody generator circuit IC UM66 (UTC), CMOS IC’s designed for using in phone etc.

Main antenna is ferrite antenna, inductance of 57mH, but you can ad telescopic antenna too, if you wish. There are 5 frequency band, realised by switching between different capacitors, which represent different tank circuits in connection with ferrite antenna, as member Sneshko proposed:

Band Selector:
ELF (3Hz-30Hz);
SLF (30Hz-300Hz);
ULF (300Hz-3KHz);
VLF (3KHz-30KHz);
LF (30KHz-300KHz).

For C5 you can use variable capacitor out of an old radio for better frequency tuning and band covering.