This small circuit is able to auto tune a radio with a toggle power/stand-by button. In this case it has been tested ok with a Sony XDR-16DBP and a Panasonic RF-D100BT DAB+ radios. At power on via the mains power adapter, the circuit emulates a power/stand-by button click to make the radio go from stand-by to power state, thus start tuning to the most recent DAB station.
Inside the radio the GND is soldered to the radio GND and the Vcc pin is soldered to a supply between 5.2 V and 5.8 V DC. For the Sony radio, Vcc is simply the power adapter voltage and for the Panasonic radio, look for the regulator with 5.2 V output !.
The PWR SWITCH pins are soldered across the power/stand-by toggle button pins.