How to control the number of beeps and flashes (an electronic clapper board).

Discussion in 'The Projects Forum' started by julianj, Apr 10, 2016.

  1. julianj

    Thread Starter New Member

    Apr 8, 2016
    I am trying to build an electronic clapper board for fun. (I am a real novice). So far I have built a very simple circuit that when a button is pressed an LED lights up and a beep from a piezzo buzzer sounds (for as long as the button is held down).

    To improve it I want the ability to be able to change the number of beeps (together with the LED flashes) from a dial. So if the dial is turned to '3' then 3 beeps together with 3 flashes will be emitted. Ideally the button is pressed only once and the beeps and flashes would last for an equal amount of time, say 1 second.

    Can anyone tell me how I might go about building this. Preliminary reading suggests I should consider using a 555 timer ic (which I have never used before). Are there any similar circuits I could study. Thanks very much.

  2. Dyslexicbloke

    Well-Known Member

    Sep 4, 2010
    That is a pretty ambitious first project ... but not impossible.

    There are of course many many ways to do it that range from mechanical to microprocessor control with discrete components, chips and transistors in the middle.

    Lets assume you dont want to use a motor or spring driven switch or hack an old telephone dial, that leaves you with a few options...

    The first and most obvious, that despite sounding a little intimidating, is to use a monolithic microprocessor. This is probably the best solution and will be the easiest to implement whilst also being the most flexible option. Bezzarly this is also the cheapest option and would be the solution used in a commercial version of your project if one were ever to exist.

    However you might want to consider going old-school just for the experience...
    If you dont have a processor running a sequence of commands then you are going to have to make a sequence some other way.
    that involves timing, and yes a 555 may be useful, along with a method of counting or cascading to get the required number of beeps.

    There are probably hundreds of ways to do this. some digital and some analogue, but they will all fall into one of three categories.
    Counting or Indexing will be most acurate. The circuit is devided into blocks or gates.
    Either you will have a pulse that is your timing signal and moves things on or chunks of circuit will time for a while and then hand control to a subsequent block.
    You could build this from discrete components, arranged into blocks, but the most practical solution would be TTL or CMOS logic.
    Within this there are still a dizzying number of ways to do it.

    It would be possible using only 555's... if your dial was a switch which 'programmed' an overall timer and you ran a second timer when the first was running that gave you a pulsed output your switch would select for the number of pulses.

    How you decide to proceed will mostly depend on what you want to learn...
    Perhaps you could build 5 or 6 of them in different ways just to compare the possibilities and learn about the basic types of circuit.

    Have fun
    julianj likes this.
  3. julianj

    Thread Starter New Member

    Apr 8, 2016
    This is a brilliant reply for which I am very grateful. Tons of help with wonderful detail. I never imagined my project would be so hard (for me) but your answer has given me plenty of information to point me in the right direction. Many thanks,