Suggestion Required to buy 3 THINGS

Projects General Guidance
1

Suggestion Required to buy these 3 things with readily available stuff ?

  1. Filters for 0 – 5V signal and over voltage protection for the analog signal for arduino.
  2. Dual Power supply with reverse voltage protection 1Amp both 3.3V and 5V.
  3. RS232 circuit TTL converter.

thx everyone..

Dr.Moobi