How to supply the power

The most simplest way is to use 12 volts battery (a smaller than car's) but you must charge frequently.
The second alternative is to use a AC/DC converter for 12 volts. You can many choices for this but sometimes you will have noise problems and unstable currents cause the unstableness of the transmitting frequency. So I suggest to add the following "3 terminal regulater" for 12 volts to the original schimatic.
There are many types of the "3 terminal regulaters" but the usability is the same.