I was working on modifying a delay timer circuit, when I heard a pop. Smoke poured out of a 470 uf electrolytic capacitor rated for 50v. Naturally it was extremely hot. I was powering the circuit with a 12dc power supply. I am not very electronics savvy. Any idea what I did wrong.
Thanks
Is this on the correct forum?

 

99.99% chance you put it in backwards.

 

I presume from your answer, I could also have applied reverse power to the circuit. If that is the case, I guess I need someone to tell me how to figure out which way I am running the power. I hooked up the positive lead on my VOM to the side of the power supply that gives me a + reading on the meter, and assumed that was the + side. Maybe I just made a mistake and hooked them up wrong one time. Does this make sense.

 

Actually I was thinking more along the line that only the cap was in backwards, but you should check the power supply connection as well if you are not sure about it.

So yes, you could have connected the power incorrectly.

 

If they are old and the electrolyte dries up, they can fail short with dramatic results.
If they are subjected to a large inrush current, they can also fail short with similar dramatic results.

 

If they are old and the electrolyte dries up, they can fail short with dramatic results.
If they are subjected to a large inrush current, they can also fail short with similar dramatic results.

Thanks for the help guys. I'm still working on it.

 

I presume from your answer, I could also have applied reverse power to the circuit.

A single diode in the positive input wire will prevent that, if that was what happened.

 

A single diode in the positive input wire will prevent that, if that was what happened.

Thank you very much. My ignorance is fairly profound.

 

Thank you very much. My ignorance is fairly profound.

We all start somewhere. I'm know where near where I want to be in electronics. That's why I try to help people starting out since I'm not that far down the road, and remember how hard it is.