i built 2 timers at max i get 3 min one timer and 7 min. on second timer. why? it says i can lenghten timer by changing c2 can i place 2 in a series(capasitors)?
i tried 2 c2 100uf in a series, it shortened the timer length. however placing 2 100uf in parallel it lengthened the timer it took 3 total in parallel to achieve 18 min. i dont understand why this should be needed. it does state 15 min timer.
Please note: as opposed to resistors, caps are put in parallel to achieve higher capacitance.
Electrolytics can feature tolerances up to 40%
Check your assembly: a wrong resistor value can influence the timing.
I have a similar problem in that the maximum time is about 3 minutes. You say check the resistors but which resistors affect timing?
R1 and C2 affect the timing. You can enlarge R1 (do not lower it or the IC can get destroyed when the trimmer is in lowest position). If you have to enlarge R1 too much for your application, enlarge C2.
Try this i did and my k2579 now runs for 65min it came with a 100uf 12v capacitor and ran for 5min i changed c2 to a 1000uf 35v capacitor works fine like i said 65min radioshack #272-1019