im a student at palo verde high school and my teacher purchased the universal start/stop timer kit k2579. we have successfully assembled the kit, but when we powered up the device we were confused on how to be sure that the timer is working properly. the red LED lights up when it is powered up and it flickers off when the stop switch is pressed. also we turned the trimmer counterclockwise as it states in the user manuel. my question is how do i set a time to the timer and how will i know that the timer is working properly after the time is set? any info would be greatly appricaiated. 
There must be an assembly problem.
Led should be off.
Led turns on when start button is pushed
Led turns off when set time has elapsed.
how do we set the time though?
By turning the trimmer (please check manual)
ok thanks, everytihng seems to be working now except that sometimes when the unit is powered up the led automatically turns on without the start button being pressed and the timer starts. Other times the unit is powered up and the led is not on until the start button is pressed and then after the time has elapsed the led turns off, so im assuming that this means that it is working correctly. 
You’ve probably put wires between the PCB and the pushbuttons and/or you are using the kit in a noisy environment.
ok
everytihng seems to be working now, thanks for the help
i noticed that in the manual that it states that the timer can be set to a time of a several seconds all the way to 15 minutes. when we have used the timer, the highest time that we can set it to is 5 minutes (that is with the trimmer turner all the way clockwise). is this normal or should the timer be able to reach 15 minutes? or does modifications need to be made to the timer so that the time can be extended? any information would be greatly appricaited.
Due to tolerances of the timing cap, actual times may vary. Replace cap. with larger value to extend time up to 60 min. Please don’t ask for values, experiment.