Hey Guys,
Thanks for the respond.
My comments to yours:
*) I did check the datasheets of course
*) I use a 74ls92 because I want to be open for extending this circuit for more than 4 states.
*) if pins are not connected internally I think I don't have to give them a defined state, am I right?
Correct, but for the sake of others:- Unused inputs (ie. pins that are internally connected to inputs) should be connected either to Vcc or Gnd. Sometimes it does not matter which (ie. Vcc or Gnd) but in other cases it does. Read the data sheet
*) am I right with connecting the reset pins like I did?
Yes
*) as I said, forget the switch at the beginning :wink:
*) if I use pin3 of the 555 then of course there is no switch, R or C for pin14 of the 74ls92 (which were indeed meant for debouncing...)
*) I will put a cap there for decoupling the IC (100nF ?)
Yes, decoupling is essential, otherwise strange results may occur
*) 4017? I will check this chip...
This is a CMOS device with decoded outputs. You can make it count in modulo 4 by connecting output 4 to the reset. It will replace IC9 & 10. There may be a 74LS version also.
Thanks
Thomas