I recently bought one very similar to this https://tinyurl.com/ygmx5d9b
(link goes to eBay) and it appears to be very easy to operate being as
there are only two parameters to set, time and temperature.

However, they don't give any help in actually using the thing, such as
what temperature to set it at and for how long!

Our first use for it is that we have some old jewellery that we want to
clean up (couple of gold chains, a gold ring with an amethyst centre
stone and small diamonds around it and a few other pieces) so does
anyone have suggestions for time and temp settings on the cleaner?

It will probably also get used for cleaning up a car part or two and
maybe a printed circuit board or two as well (not at the same time), so
what settings would I use in those situations?