I'm looking for a general rule of thumb how to protect the circuit when it's not specified.
- First case, when should I use a fuse/regulating resistors?
For example I know I should put a resistor before a led for regulating the current that it won't pull too much and burn itself.
Do I need it for ICs (AVR mC, 74XX..)?
HD44780 LCD (on the VCC should I put a 100 oHm resistor)?
How much resistance should I put?
- Second case noise. When should I use a decoupling capacitors?
How and what capacity?