• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Random timer circuit required

Not open for further replies.

Tako Kichi

New Member
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,



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.
Not open for further replies.

Latest threads

EE World Online Articles