I don't personally know of any timers that run like that. I have some digital timers that can do 1 minute apart but only have 8 on/off cycles per day. I also have manual timers that have 15min on/off cycles but thats about it. I have found that when using a grow tent it is best to just use a constant exhaust as it will hep keep negative air pressure on the tent and keep any unwanted odor's form escaping in between exhaust cycles. I have grown in tents for a couple years now (using for vegetation rooms at this point) and this is how I have gotten the best results.