So, i have two 12V 4A devices and only one transformer of 12V 5A.
Can i connect both to the same transformer together, or if i connect both, the transformer will have to deliver 8A?

 

Hello,

NO, you can only use one on the transformer.
Using both together will burn the transformer.

Bertus

 

Hello,

NO, you can only use one on the transformer.
Using both together will burn the transformer.

Bertus

Thanks!

 

Note that if you add a rectifier/capacitor to get DC from the transformer (as implied by the thread's title) than you need to derate it to 50-60% of its AC rating to avoid overheating.
A rectifier/capacitor draws high peak currents from the transformer which causes higher I^2*R heating in the transformer than the rated AC sinewave current.