Hi,
Are there any guidelines as to when to end the thread generated by the first thread and start another thread?
There are no clear boundaries. I recommend using your thread's title as a reference.
If your new question somehow catches up with the title, stay with your thread.
If your new question is unrelated to your title, then start a new thread.
***
Please also read the forum rules.
They also say that you should choose the right forum section.
You posted this question in: Hardware and PCB Design > Hobby Circuits and Small Projects Problems
..but the question relates to the use of the forum...
So now moved to: The Classifieds > About EDAboard.com
Note that each forum section includes a brief description of what type of posts go there.
(Like this example: Hobby Electronics Circuits, circuits samples, electronics in house and in cars, amplifiers, subwoofers, trasmitters, receivers, generators, meters.)
Klaus