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The 7805, and in general all 78XX voltage regulators, has all sorts of internal protections, including Internal Short-Circuit Current Limiting, Output Transistor Safe-Area Compensation, .. , Internal Thermal-Overload Protection ..
If they are not exposed to higher voltages they are rated for, they will not fail ..
To step-down from 9V to 3 or 3.3V you can use fixed voltage regulators (go google), or you can use the very popular adjustable voltage regulator: LM317 .. see picture below ..
- 1.25V in this formula represents internal voltage reference ..
- 240Ω is the recommended value for R1 ..
- R2*Iadj is very small and can be removed from the equation ..
Taking into account all of the above, for 3.3V output voltage the value of R2 should be ≈394Ω (the closest choice 390Ω) ..
on that case you show to me. the electricity go through the LM317 and not to save to the capacitor first, your first picture LM317 which are there 2 capacitor polarized and non polarized, so electricity could save to them. which save can i used for my regulator?
if i used your first picture your calculation based on datasheet is not match ?
CMIIW
Added after 27 minutes:
i want to ask about the value of C1? are same with value of C2?
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