urgent help needed!

[gut_but]

hi
pls help in designing a circuit or design idea suct that it produces 3 or 4 cycles of oscillator in and then stops after that.

newbie

 

[bonxer]

Frequency? Accuracy? Application?

Without any details, I'm immediately going to suggest the simple 555 timer for the oscillator, a counter (maybe a 74LS93), and a combination of logic chips to determine when the output reaches the desired end state. Counting to binary 8 seems easiest (least significant bit goes 0, 1, 0, 1, 0, 1, 0, 1, then finally goes back to 0). Detecting an 8 is easy. It's the first time the most significant output Q4 goes high. When that happens, turn off the counter's enable, so it stops counting. There's your four pulses. Want 3 instead? Have it count up to 6.