1: witch pcb boards on ebay i can find to detect low voltage current then trigger something, same with high voltage , this is for test purpose so will love to know and play with it.

2: what pcb boards i need to do some as if ch1 output signal detected then do something , if ch2 signal is detected then do something else..


like if or else statement in code what pcb boards does that

 

low voltage current

Ohm's Law: Voltage=Resistance x Current
Electrical Power: Power=Voltage x Current

What is Voltage Current?

 

Voltage Comparator Information And Circuits look at the various comparators. Spark Fun among other vendors at one time did market ready to go boards.
Another option is the use of a uC (micro controller) such as one of the Arduino or similar family. Learn how to apply Hysteresis to either a comparator or uC based system. Your best bet would be to start learning how to program a uC because it offers plenty of I/O (Input/Output) and you write decision making code. Start learning Analog to Digital decision making, that would be the IF, Else, Or you mention and a host of others.

Ron

 

1st guess: http://www.ebay.co.uk/sch/i.html?_sop=12&_sacat=181693&_nkw=relay module