This inverter circuit can provide up to 800mA of 12V power ... properly without the need of the transformer. This 6V to 12V dc-dc boost converter can drive a load in 12V about 3A current. The 555 ...

This, of course, isn’t true. Alternating current (ac) or direct current (dc) circuits are capable of carrying very different currents, as illustrated by the ratings on the switch in Figure 1.