A few years ago, I made several DSP radio consisting of wrapping wires and universal circuit board as shown in the left side of the picture. In those days I did not use Eagle or some cad soft, just I made I want.
It is still surely working but I did not make notes of schematic (indeed it has gravity sensor, RTC and DSP radio) and I myself don't remember the details and this time I make it a bit smarter form.
This is the whole schematic. In the schematic I should point out "AT42QT...." in right-down part is just put to use SOT23-6 form factor and real parts number is TP4057, LiPo charging controller. JP2 is antenna terminal and even 21st century, yes we need analogue part, ANTENNA! between 5-4 of JP2 should be connected to ferrite-bar antenna (or relevant) and 2-3 pins are "antenna terminal" for shortwave and FM radio.
It consists of KT0915 and ATmega328. KT0915 is a I2C controlled DSP radio chip and Mega328 controls whole system including OLED display. On OLED display, frequency information and stereo/non-stereo RSSI for FM reception is indicated. This is not character OLED and more attractive user-interface will be possible (I did not yet) .
Receiving band switch is inside rotary encoder and just push frequency tuning knob will change:
(band 1) AM (535-1620 kHz) (band 2) FM (70-108 MHz) (band 3) SW 2250 kHz (band 4) SW 3150 kHz (band 5) SW 3850 kHz (band 6) SW 4700 kHz (band 7) SW 5900 kHz (band 8) SW 7100 kHz (band 9) SW 9400 kHz (band 10) SW 11500 kHz (band 11) SW 13500 kHz (band 12) SW 15000 kHz (band 13) SW 17450 kHz (band 14) SW 18850 kHz (band 15) SW 21450 kHz (band 16) SW 25600 kHzafter band_16, frequency will go down to AM again. Actually reception frequency does not have "limit" and more than 30MHz is also covered (I don't know what will be received?). It seems "as far as PLL locks". I did not implement in the code but I confirmed aviation frequency (around 130 MHz) is also covered. (aviation is AM modulation and this radio supports FM only in that frequency, so very small volume voice, unfortunately)
In all cases, battery problem is a headache. When I use radio at bed-side(mostly before sleep), battery shortage is quite annoying me and I love rechargeable one, so I put Lipo charging circuit.
USB terminal is not for programming but just providing charging voltage (5V). During charging, red LED will turns on and,,
Full charge will turn green LED on.
As same as my recent another project, clean PCB is prepared and very limited number (just 3) parts kit is prepared.
Now it is on sale at tindie.com. If you have some interest, please don't miss it!