Hi Folks,

I wonder if someone on here can help me with a circuit design. It has been MANY years since I last did any circuit design projects and I am very rusty (to say the least) and I am sure that there are many chips out there that simply didn't exist when I was last playing around in electronics. My circuit building skills are probably still ok but the designing skills have gone (the old use it or lose it syndrome!)

I have searched the web and every posting on this forum but have found nothing suitable yet.

Let me explain my problem. I have been asked (by a friend of a friend) if I can come up with a device that will generate a random time interval between .5 and 90 seconds and then randomly select between two different audio outputs (for example a continuous tone or a series of beeps). I was thinking a simple NO push-button switch would be the trigger to start the timer with the output coming from a piezzo (sp) buzzer. There needs to be a random delay (different with each button press) between the button press and the audio starting. The audio would only need to last maybe 5 seconds before resetting to the start condition. This would have to be a hand-held unit so we are probably looking at a 6 or 9 VDC power supply (PP3 battery?)

Does anyone know if such a circuit exists, or of a modifiable one. If not could someone come up with a simple circuit for this application.

Any help would be greatly appreciated,

Thanks,

Larry

p.s. A single beep/LED flash on the button push could be a useful thing to have too so that the operator is sure the device started the timing sequence!

p.p.s. A pseudo-random timer would work too! This device would be used to start contests and the participants should NOT be able to anticipate the start time - hence the need for a (pseudo) random timer.