astable 555

Do you mean you want to syncronize the astable somehow? The astable

--- _____ Connect the output of the monostable to the RESET input of the astable. The astable will run while the monostable's output is high.

I have a board that inputs 8 pulses to a counter and after the 8th count it is to trigger a one-shot 555 which will start a delay for about a min. Then the one shot needs to trigger the oscillator after the delay.

Your description is fully unclear (to me). What do you mean by "trigger the oscillator"? Is the oscillator is supposed to run until the monostable starts and run again when the monostable has timed out? If not, what will stop the oscillator and when?

petrus bitbyter

berichtnews: snipped-for-privacy@j4g2000prf.googlegroups.com...

The monostable is acting as a delay of approximately one minute. The astable should be off until the delay is up. Then I want the astable to start oscillating.

So at the third attempt you have almost managed to tell what you are actually trying to do. I assume this is homework and needs to be completed by the end of the week.

What you are describing is a 'Gated Oscillator'. Read the words I have just written then go back to your lecture notes and look for 'AND Gates' amongst your material on 'Digital Logic'. If your lecturers have done a half reasonable job you will find what you need to know.

If you still cannot make sense of it go to sci.electronics.basics and someone will answer your question there. After that I suggest you give up trying to be an electronics design engineer and try journalism.

schreef in bericht news: snipped-for-privacy@j4g2000prf.googlegroups.com...

As far as I'm informed now, you should make the monostable trigger a flipflop which in turn can start the oscillator.

BTW. Your understanding of electronics looks like very minimal to me. You're apparently a newbie rather then a designer. You still did not answer my questions, even don't seem to understand why I asked them anyway. Better post in sci.electronics.basics next time.

petrus bitbyter

you can use the reset pin to stop or start it.

Bye. Jasen

Sure: View in a fixed-width font such as Courier.

. . . . ___ . ENABLE/RST>-----------------. . | . | . -------------- . | RST | . V+ | | . from mono | | DIS OUT |----. . --------- | | | | . | | [10K] | | | . | | | | | | .--- ->-||-[1K]-+---| THR/TRIG | | . 0.1u | | | | . [10K] -------------- | . | | . --- | . | . -------------- _ _ . | RST | | | | | .. . | |- - - . V+-[1K]-+--| DIS OUT |-------->

. | | | . [Rt] | | . | | | . +--| THR/TRIG | . | | | . Ct | -------------- . === . | . | . --- .