How do you set the C17D3129 atomic projection alarm clock

if its atomic it needs to be in a place were it can receive the signal well, put it on auto & leave it on a window sill for a while & it will set its self, mine does.

would like to set the correct time

http://www.lacrossetechnology.com/5110/manual.pdf

Please check this answer:
http://www.fixya.com/support/t3486802-set_clock

This site lists several including some desk models on two pages and each has unique downloadable instructions.

http://www.klockit.com/depts/AtomicClocks/dept-52.html

This one may fit the bill...

http://www.klockit.com/PDFs/lacrossemanuals/WT-5360U.pdf

I have one of these, and look for the manual on the 'Net every time DST changes, and eventually figure it out. Here's how: (1) Hold down the ALM/SET button until you get past the alarm setting and you see 24H or 12H. (2) Step through the settings by pushing the ALM/SET button, changing each as desired by pressing the +/CYCLE button. Eventually you'll wind up with the time zone indication flashing (it's really tiny, and appears just below the time indication). Press the +/CYCLE until you get to the desired time zone. (3) After the screen quits flashing, press the -/DST button to get the desired setting. I hope this helps, and that I can find this post again next time change!

Please check out this answer:
http://www.fixya.com/support/t3486802-set_clock

No. I didn't "fiix" it. I only wanted to know how to set it. I have lost the instructions. Thanks, Pat

I just pressed and held for about 3 to 5 seconds the button with the +/- on the bottom of the clock and until it showed the part of the US that I was in.

try looking up the manual on the model number you might find it online. I have the maual for this model.