Hello everybody. I am new to this forum, (and to electronics). I am struggling to come up with a strobe for a model airliner: wing tips and red top and belly. Found a calculator that gave me this formula with the 555: R1 22K ohm R2 1K OHM, C 100 uf, T1 off 1663 millisec, T2 flash 138 millisec, Hz 0.000554, I am trying to get the flash every second and a half or so, but I get the opposite effect: the led stays on for 1.5 sec, then a brief off. What I am missing. Can somebody point me in the right direction? Thanks.