Hi-
I’m working through the book “Learning the Art of Electronics.” The project I’m having trouble with is attached.
I carefully wired this and double-checked to make sure there were no mistakes. I omitted the decoupling capacitors (on the supply line) as the instructions stated— they said to install them afterwards and listen for the effect.
I never got to do this. I switched on the power, and heard some hiss noise coming from the speaker, as expected. I set the function generator for a sine wave, 300 hz, .5 volts amplitude, and switched it on. I heard the tone on the speaker for about 3 seconds, then silence and a small poof of smoke.
Thinking I might’ve made a mistake, I checked everything carefully, then used the 2nd amplifier that I had and tried it again, with the exact same result.
I’m not sure this is relevant, but the bookshelf speaker that I’m using has an auto-shutoff to protect it from being over-driven. Although the volume wasn’t particularly loud, I’ve seen it shut off in the past from a quiet volume because it didn’t like the home-brewed signal I was sending it. Keeping in mind that I don’t know what I’m talking about, I was thinking that maybe the speaker shutting off caused some kind of inductive spike that overloaded the amp?
Here’s a link to the amp’s data sheet:
https://www.ti.com/lit/ds/symlink/lm4667.pdfThanks so much for any help you can provide.
-John Adler