Relay turns on when computer is disconected

Jonathanw82:
Hello All

Then wiring diagram was for illustration purpose only it was the first time I had used fritzing.
The circuit was already made on strip soldered board. (it was not wiring).

Can I suggest that is the last time you use Fritzy.
It is not good a representing signal or power flow, there is the occurence of LOW RES images which yours unfortunately is an example. (Not your fault.)
Can you post a proper schematic using pen/pencil, ruler and paper please.
The advantage is your hand has ALL the schematic symbols programmed in, all you have to do is draw them.
There are some good free CAD programs available, but don't go worrying about them at this stage, just get a schematic on paper.
Some CAD progs are KiCad, ExpressPCB, and others, that will be suggested.
Thanks.. Tom.. :slight_smile:

4.6V as a HIGH on a digital output is about right, it can be from 5V to 4.2V output.
The diode is a good fix.