Another DIY project I’m currently working on is a radio based on an ESP32. I used a very cheap, old, and faulty Siemens RS-555 radio as the foundation, meaning I removed the old electronics from the radio and am now building it up piece by piece with new components. The original controls of the radio are being preserved and I’m trying to maintain the original functionality of the radio as much as possible and where it makes sense.
As mentioned the foundation of the project is once again an ESP32. In addition I’ve incorporated a preamplifier board with controls for volume, bass, treble, midrange adjustment, etc. as well as a main amplifier with 2 x 50W power to drive the speakers. The radio reception is handled by a Si4735 chip.
You can find the source code for the software on my Github.
The hardware components used include:
- ESP32-WROOM-32
- A preamp module based on NE5532P
- A 230V to 18V transformer for powering the preamp and other components
- A 2x50W amplifier module
- Si4735 for AM/FM radio
- Adafruit MusicMaker Feather for internet radio/Bluetooth/MP3
- Several PCF8574 and one PCF8575 module for connecting the front elements
- An INA219 module for measuring power consumption
- 2 adjustable buck converters for 3.3V and 5V to power the ESP32, etc.
- A BMP180 for temperature measurement
- A 4-channel and an 8-channel relay for switching the inputs and outputs
- A DS3231 clock module
- A 2×16 character LCD display based on HD44780
- A 32×8 LED matrix display based on MAX7219
- Plenty of cables, connectors, resistors, capacitors, etc.
The ESP32
The ESP32 is mounted on a breakout board. I added a connection for an external WLAN antenna, and various capacitors for power supply buffering are placed on the bottom board.
Si4735
Another core element of the project is this chip. It is responsible for radio reception. I chose this variant because it allows me to receive both FM and AM radio, just like the original Siemens radio. The large board on which the module sits was built according to the documentation for this chip. Currently, I only have an FM antenna connected, and I still need to build a connection for an AM antenna.
