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

 

For RS232 converter, I use MAX232 or MAX233 (if you want to eliminate four capacitors).

 

A complete RS232 to TTL shifter is available from Sparkfun Electronics, as well as others. and can be seen at this link: [URL="https://www.sparkfun.com/products/449"]RS232 Shifter[/URL]

 

1. Filters for 0 – 5V signal and over voltage protection for the analog signal for arduino.

Which analog signal is this? What are you looking to protect it from? ESD? Lightning strikes?

2. Dual Power supply with reverse voltage protection 1Amp both 3.3V and 5V.

What is driving this supply? Some AC line? Batteries? Solar cells?

Is this supply itself potentially vulnerable to reversed polarity, or is the unit connected to it's output vulnerable? Note a supply cannot protect you from connecting it backwards, it only "sees" the world thru it's two output terminals (and they never move).

Plugs with defined orientations are available.

It may be cheaper to get a 5V supply and add an external regulator for the 3.3V.

3. RS232 circuit TTL converter.

MrChip made some excellent recommendations.