Over heated voltage regulator
The transformer secondary is 12 - 14 volts AC so, assuming 14 volts, it will have a peak voltage of 19.8 volts. After bridge rectification this becomes about 18.4 volts DC and the 7805 regulator is dropping 18.4 volts DC to 5 volts DC whilst taking 200 mA.

The 7805 power dissipation is (18.4 volts - 5 volts) * 0.2 amps = 2.68 watts. So, without a heatsink, the 7805 will boil.

You might want to read this article that describes the problem in more detail and offers a switched mode buck regulator as a solution: -



The device above is from TI and is called a TPSM84205. It will efficiently deliver 5 volts without the excessive over-heating: -