I need a circuit that creates two beeps only, with the following functionality:
- a temporary push switch is attached to the circuit
- once the push switch is pushed for an unspecified length of time the circuit should do the following:
* beep for the first time for ~500ms (at the time the switch is pushed)
* wait x seconds (variable based on potentiometer - e.g 3s)
* beeps for the second time for ~2s
* if the button is still pushed, the circuit will not re-trigger unless the button is pushed again.

Note: I have done the first beep with a 555 (see attached), triggered on the negative front but I don't know what would be the easiest solution to add the second one.

What would be the easiest approach for the functionality described above(not limited to 555 is the solution is better)?

Thank you,
Flavius.

 

Use the beep signal to trigger a separate 555.

This can be done with a 556, which is two 555s in one package.

 

Thank you. I understand your suggestion that I can trigger the second 555 which will give me a beep of ~2s, but how do I do to trigger it only after x seconds (variable) from the first one?

 

You set the second 555 for the amount of time to delay before triggering the ~2s beep

Set yourself up a second 555 circuit for a ~2s beep, x seconds after triggered from a button.

Then attach the out from the first, to the trigger of the 2nd.


Are you catching what im saying?

 

See if reading this will help:
http://forum.allaboutcircuits.com/blog.php?b=378

This is Bill_Marsden's articles on 555s.

 

You want to use 9VDC or what?

I'd use a monostable that controlled a slow oscillator, timed to where only 2 beeps came out.

Does it matter if the beeps aren't quite the same duration? Most 555 oscillators have a long first pulse, which will be noticeable. There are fixes for this, but it just increases the parts count.

 

Bill, The first beep is .5 seconds, then x amount of time must pass before a 2s beep.

 

I am sorry, but I don't understand how to do it.

I know that I can set the output time of the second 555 using the RC constant (~2s), but I don't understand how to do the delayed trigger (x seconds).

If it is not too much, a picture will help me understand better.

Thank you.

 

OK, I missed the short beep / long beep requirement. It is still doable, but I gotta think about it.

How about a 4017? Just clock it at a constant rate and select the outputs that match the beep requirements. It would allow for the delay too.

Nope, that ain't it. It will probably require a 555 per timing duration, especially the variable durations, 4X 555's perhaps. You can use 556's to reduce parts count, but for now figure 555's. Use diodes to allow 2 of the 555's to turn on the piezo, the other two are dead space.

BTW, the drawing you have is one I made for another thread a while back.

 

post #5 I gave you a link. There are many pictures there.

 

Bill,

I have already started reading from your page, but it may take some time until I go through everything. Very good resource. Thank you.

The drawing is take from another thread, indeed. Thank you for the very good quality of your posts and for taking time to help others (including the drawing I am using).

I will go ahead with 4x 555.

In the meantime, if anybody has any other idea that may involve less components, I would appreciate your input.

Thank you,
Flavius.

 

OK, here are a couple of pages that will help with 555 designs.

http://forum.allaboutcircuits.com/picture.php?albumid=41&pictureid=308

http://forum.allaboutcircuits.com/picture.php?albumid=41&pictureid=977

I could have displayed them entire here, but they are pretty large.