Alert noise maker


Frequent Poster
What if I wanted to create a device that will play audio with a logic signal on? Either playing once or repeating. Where would I start?
It could be but it would be 10 times less cool. I might as well tell you what I want to do.

I want to make my battery charger alert me when it's done by playing the tf2 medic noise "I am fully charged!"

I would just use the led logic on for the signal. (led turns off when it's done so I just use a NOT gate.
QuickSkop3 said:
Could get annoying after a while though
That's why I pull the charger out of the wall. It's not good to leave them in there forever, that's the point of the alert. But I cannot figure out how to build one.
That radioshack module will do what you want just record the audio through a jack then build a circuit that some how knows when its fully charged, a relay maybe? or you could integrate it into the charger just hook up the power to the green LEDs prongs(asuming its a smart charger).
No it's just a normal nimh aa/aaa charger that has an led that turns off when it's charged. I suppose I would have to mod in a prebuilt one in there. How can I make it replay it self. Would a really slow crystal work? (digital on off switch?)
Alright. On a side not though how can I play a tone out of a speaker. I basically want to make multiple tones come out of a speaker. I don't have an AC power supply. So what kind of rectifier can I use to turn say 3 volts into a simple tone?

The potentiometer changers the tone. Change the values of the resistors and capacitor to adjust further. We used a 9V power source but it should work down to 5V or so with reduced volume. R1, R2, C1 and the potentiometer affect the tone. R3 is the base resistor (is that what it's called?) for the transistor, I recommend you leave it unless you drastically change the supply voltage. R4 affects the volume of the speaker, it's probably reasonably safe to leave it out except for tiny speakers.
I had to get some new speakers from mouse so I picked up come 555's with it. Thanks guys. 555's are nice.