I know there are so many novice questions on these forums, can you answer one more?
I want to create a sound activated LED, that is activated by *any* noise, and ideally the LED will stay on for say 30 seconds before switching off. The most important aspect is that it needs to be as small as possible as it will fit within a tiny space. This also means that it will need to run of tiny button batteries. I have read the many threads in the forum that have asked for similar advice as well as having found many circuit diagrams on the net, but they all have one of the following points:
1. Either the components seem many and the circuit very large
2. Or they run off large batteries.
I remembered them keyrings from the 80's that beeped and flashed when you whistled, so I bought a couple off ebay and took them apart. I was amazed at how minimal the circuitry is, it's ideal, but the led flashes too many times and of course it beeps, and it only activated when whistled at. I have inserted an image below.
**broken link removed**
So here are my questions:
1. Is it possible to modify the circuit above so that it doesn't flash.
2. Is it possible to modify the circuit above so that it stays on for a while?
3. Is it possible to modify the circuit above so that I can get rid of that irritating beep?
4. Is it possible to modify the cicuit above so that it is activated by any noise and not a whistle? Where is the filter that determines the frequency?
5. Is it easier to make one from new?
6. What's that big black blob? Is this some kind of microcontroller?
I have got my Electronics for Dummies book but in the mean time a point in the right direction woud be very much appreciated.
Thanks
D