Badge Radio

 
First, the hardware design:
The RAD5807 integrated radio IC is used as the main chip, and the radio function can be implemented using a few discrete components.
(Here's a note about a potential pitfall: although pin 6 of this chip is GND in the LCSC component library and the chip datasheet also lists it as GND, a pull-up on pin 6 can actually eliminate the need for an external MCU; a switch can be used to adjust the radio channel and volume.)
To reduce power supply interference to the radio (virtual detection), I used a 0Ω resistor to connect the analog ground and digital ground.
To reduce costs, the two tantalum capacitors C33 and C34 can be replaced with ceramic capacitors.
Note: There are two positioning posts at the bottom of the headphone jack. To maintain the integrity of the front panel, I modified the package to remove these two positioning posts. Please use a utility knife (be careful) to trim these two positioning posts when soldering.
Regarding the power supply: To reduce the number of components, this design directly uses an ETA9697E8A (a bit obscure), but it is available. It has a built-in 5V boost converter; the output will shut off if the battery voltage is too low, and the charging current can be configured via a resistor. Therefore, it can be directly charged using Type-C (this design uses a 6-pin fully surface-mount Type-C connector; please check if you have it in stock). It has two indicator lights: one for starting charging and one for charging complete. It automatically stops when fully charged. The push-button switch uses a pinless design (because the front is colored silkscreened, we wanted to avoid using positioning posts to prevent damage to the front pattern).
It uses a 2032 button lithium battery, note that it's a button-shaped lithium battery with a 3.7V voltage
(why doesn't the RDA5807 use a 3V direct drive instead of a button battery? Answer: Dry cell batteries cannot be recharged, the casing is glued on and cannot be removed, soldering copper nuts on the back is troublesome, and we couldn't damage the front pattern, so we finally decided to use a rechargeable battery).
Switch part:
(This SW2 side switch also requires removing the positioning posts).
If buying materials one by one is too troublesome, we may release a material package later including a 3D printed shell. (Please find the circuit board yourself, thank you).
Attachments include a demonstration video and shell STL files.
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