I started a new project: Groundhog day clock. Their version uses a Adafruit xf sound board, where as mine will be using the cheapest MP3 player I could find on Ebay. The problem that I will encounter is pressing play on the player. There is a 12v power trigger going to the board, from which I can tap into and drop the voltage to 5v for the player. So when the player turns on, I have to pause for about 5 seconds for it to boot up before hitting the play button. This is where I hope to use some variant of the 555 time delay circuit. But what I'm wondering is how to stop the trigger after a few milliseconds. Any ideas?
If you do not know how the play button is wired, then the safe method is a relay. It bridges only the button contacts.
However you might be able to do the job with a 555 (or other IC, or transistor), but you must find out which wire goes to the button. One wire goes to turn on playback. What about the other wire? Is it supply positive, or supply negative?