I looked at the answer to "How to turn a 555 in astable mode into a decaying square wave" but this is really for an input to a speaker. I want the input to go into a counter to count the number of square wave pulses. I thought of using 2 555s the first one generates a square wave the second in monostable mode generates a square wave of some length ( acting as a modulator envelope). Then combining them with an AND operator. What do you think of this idea or is there a simpler way? I should explain in more detail what I am trying to do. I have a 4 digit Digital Counter panel meter. There are 2 input leads when the input is high the counter increases by 1 . It also can increase by1 if I connect the input to a switch. When the switch is closed the counter also increases by 1. What I want to do is have the counter increase by fixed number. So say the switch is closed and I want the counter to go up by 5 or see set number.
You can do this with a pair of 555s, or a 556 (just two 555s in a single package), by using one as a monostable to enable the other, acting as an astable, for a period that generates the number of pulses. If I were doing it, it's probably cheaper and simpler to program a PIC or similar to do this, there are plenty of 50 cent microcontrollers that will do this - plus you could use another pin or two for up-down adjustment of the pulse number.