PixelRadio is a FM Radio Transmitter with RDS (Radio Data System) capabilities. Hardware consists of a ESP32 WiFi equipped Microcontroller and low cost QN8027 Digital FM Transmitter module. Typical range is about 100 meters with a small vertical whip antenna.
Build documentation is just a one page schematic. Step-by-step wiring instructions or pictorial wiring diagrams are not provided. The soldered parts are through-hole type. No SMD components need to be soldered.
Any component sources that are mentioned are for your convenience. Please feel free to use your favorite supplier to acquire parts.
Kits and/or ready-to-use products are NOT available. The project's creator does NOT sell any item used in this project.
Please visit the Parts List section for the project's bill-of-materials.
PixelRadio can be built using Perfboard construction. However, a Printed Circuit Board (PCB) is recommended to ensure proper operation of the RF amplifier circuitry.
Artwork files are provided for the two-sided PCB. The PCB files are in the RS274X Gerber format required by commercial PC board fabricators.
The PCB is 95mm x 100mm in size. It is specifically designed to slide into a low cost metal enclosure. See the Parts List for details to the enclosure.
| PCB VIEWS | Click each image for larger view |
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The schematic is the main reference for building the circuitry.
Flush cut all component leads on the solder side. Clean off all flux residue using solder manufacturer's recommendations. "No-clean" flux must be removed on all components in the RF circuitry area.
Solder jumper wires at locations L7 and J9. Discarded resistor or capacitor wire leads work well for this. It's also possible to install a 0.1" 2-Pin header at J9 and use a shorting block instead of a soldered wire.
Mount the ESP32 module with two 15-Pin Header Sockets. The added height from the sockets will provide proper clearance to the mounting tab on the 3D Printed end panel.
The CD4052 IC (U1) can be installed in a 16-PIN DIP socket. However, using a socket at this location is not necessary.
The QN8027 RF Module must be installed directly on the PCB using the SIP Header pin strips included with the module. The header strips will provide a 2-3mm gap between the main PCB and the RF module. Do NOT use a plug-in socket to mount the RF module.
The green "Music On" LED requires long leads to reach the front panel. Before soldering, temporarily position the enclosure's front panel and bend the LED's leads as needed. Then solder in place.
Note: The Music On LED will be illuminated when the external audio (music source) is enabled. It will turn off whenever the Test Tone function is active.
The LilyGo TTGO-T8 ESP32 MCU includes a 2-pin wire pigtail cable.
Solder the cable to the P1 (VBAT) pads on the PCB;
Red wire to the 5V pad and Black wire to the GND pad.
Plug the ESP32 into the PCB socket (orientation is shown in above photos). Plug the 2-Pin P1 cable into the ESP32.
Set the ESP32's power switch to the ON position.
The power switch is next to the RST push switch and the ON/OFF positions are labeled by its silkscreen text.
To turn it ON simply slide the switch towards the RST push switch.
Important: The ESP32 will fail to boot if the Power Switch is in the
OFFposition.
The telescoping rod antenna looks nice and works well. However, a 30" piece of bare or insulated wire can be used in place of the telescoping antenna. Install the antenna so that it points upwards or downwards (vertical polarization).
For more range a dipole antenna can be made from easy-to-obtain hardware store items.
Assembly instructions are published at the doityourselfchristmas.com site:
DiY Dipole Antenna
A 5V or 12V LED "On Air" indicator can be installed at J8, as follows:
J8-1 SIG: LED GND (-)
J8-2 12V: LED 12V Power (+), max 1A
J8-3 5V: LED 5V Power (+), max 250mA
The recommended enclosure is aluminum construction, which will shield the ESP32's antenna. This will reduce WiFi signal strength. Replacing the supplied metal end panels with PixelRadio's 3D Printed plastic parts will provide better WiFi range.
For best WiFi performance the ESP32 can be updated to use an external 2.4GHz WiFi antenna. This will increase WiFi range and improve wireless network connectivity. The ESP32 has a u.FL (IPEX) connector for connecting the external antenna. Enabling it requires moving a 0402 size SMD resistor.
The resistor is a 0-ohm jumper that normally connects the RF signal to the PCB mounted antenna. Moving the resistor disables the internal antenna and re-routes the RF signal to the u.FL connector. Be forewarned that it is a tiny 0402 size SMD component that requires good SMT soldering skills to relocate.
| FACTORY INTERNAL WIFI ANTENNA | EXTERNAL ANTENNA MODIFICATION |
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Along with moving the resistor you will also need to purchase an 8cm long SMA to u.FL cable and mating 2.4GHz WiFi antenna. The project's 3D Printed End Panel includes a mounting hole for installing the external antenna.
Note: The cable and antenna are sold in two variants, SMA and RP-SMA. Either can be used, but do NOT mix them; If the cable is SMA then the antenna must also be SMA.
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Please see the Project Software section for details on flashing the PixelRadio firmware.
PixelRadio is a digital device and does not have any adjustable components that are typically found on analog designs. Therefore RF Calibration is not required.
All information is provided as-is. YOU must accept all responsibility for the construction and use of the project.