Step 6Now to remove the TuneCast auto-power down
This step is a bit trickier, it involve adding a switch, a resistor and some wiring.
The idea works by biasing up the bit that turns on the TuneCast when a audio signal is present. Although the transmitter is battery powered, many of the ICs on the device requires a higher operating supply voltage, this is done with a boost converter, boosting its internal supply to around 5V, where it is kept permanently 'on', which partly explain why your TuneCast is dead after a few days even if you're not using it, pretty dismal, but great for this modification!
Note on the photo below, the two point in which the wires are attached is where you need to modify ( incidentally, this is at the top right end of the PCB, on the LCD side) . I choose to use enamel wire, which has a coat of thin insulating enamel/plastic, simply scrape the ends to allow soldering.
The second image is a drawing of the circuit connection.
As promised, with this feature allows you to 'swamp-out' a typical commercial FM station within 2 to 3 meters of the transmitter and enjoy the peace and quiet. Not dramatic but enough to convulse the listener into fiddling with the radio tuner. ;)
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