Don't pout, @cmartinez
You have a new toy and I'm smoking you on simple stuff. In a month you will be simulating circuits that I couldn't do if I had all day.

... nah... not pouting here... just trying to see if I can learn something new along with the OP.
RMS of circuit in post #12 (the irony!) is 17.52 mA, according to LTspice... isn't 100 hours too long for this amount of current on a couple of AAs?

 

View attachment 93749 ... nah... not pouting here... just trying to see if I can learn something new along with the OP.
RMS of circuit in post #12 (the irony!) is 17.52 mA, according to LTspice... isn't 100 hours too long for this amount of current on a couple of AAs?

would you stop petting my head?! I'm drowning in "likes" down here!! ha ha ha...

 

would you stop petting my head?! I'm drowning in "likes" down here!! ha ha ha...

You just quoted yourself to tell yourself you are drowning in 'likes'? You feeling ok? Have you been near one of those 'grass' fires. I heard the smoke down your way gets kind of freaky.

 

isn't 100 hours too long for this amount of current on a couple of AAs?

The worst estimate I can do is 28 hours with alkaline batteries. You are assuming continuous duty with an unceasing wave. I am expecting the LED to light with the beats of the music, for less than 50% duty cycle, and the kid won't run the music all the time. Even if this, "human factor" is useless, there are only 24 hours in a day and the batteries should last at least 28 hours.

 

You just quoted yourself to tell yourself you are drowning in 'likes'?

I waited until the thread was about finished before I, "liked" about a dozen of his posts.

 

Good work, @#12 and @cmartinez ! You have earned the AAC Hero-of-the-Day award!

You saved Halloween for some little kid. Depending on the kid, and the skills of the dad, the guy may be a hero in the kid's eyes as well - hopefully.

 

I had a good TS to work with. I didn't have to teach him how to solder and how to find the collector of a transistor.

 

Good work, @#12 and @cmartinez ! You have earned the AAC Hero-of-the-Day award!

You saved Halloween for some little kid. Depending on the kid, and the skills of the dad, the guy may be a hero in the kid's eyes as well - hopefully.

Thank you, thank you Gopher... it's good to see you can recognize talent when you see it... but truth being told, I had a great sidekick... couldn't have done it without him...
Seriously now, the TS got to me from his very first post, saying that this was important to his kid, and that his kid is important to him, of course. AND... I don't as nearly understand how the circuit really works as you guys do. As I've said in earlier posts, I'm only a half-baked amateur trying to learn and teach at the same time... (the teaching part is the dangerous part here... always risking saying something stupid)
Gotta hit the sac... I have a busy day awaiting me tomorrow, going to the mountains to my brother's place. I'll post some pics in the picture this thread on Monday. God willing... nighty night.

 

God willing... nighty night.

Me too!

 

@cmartinez and @#12 - Great work. For future visitors to this thread, as it is too late for the TS, there is a circuit using an op amp that can also be used. The audio input is amplified to a 0-4VDC (approximately) signal which can then be used to drive an LED driver. The output in the schematic in this thread labelled ADC OUT is where the signal can be taken from (there is also an amplifier, which need not be used.) C4 can be reduced to make the circuit more responsive.

 

Spinnaker PM'd me about this circuit so I had to get down with the math. In doing that, I saw that rechargeable batteries will not work because they typically deliver 1.2v to 1.25v. That is not enough to drive an LED through a base-emitter junction. Even alkaline batteries will not drive a blue or white LED, but they should work with red.