Capacitor overheats

I have made a Shield for a UNO to the circuitry in the attachment. I power it with a standard 9 V battery and it connects with the other boards in the RC network just fine. However, after a minute or so the capacitor is far to hot to handle and the communication dies.

Is there some obvious reason (given that the board complies with the circuit diagram) for the overheating and consequent failure?

Thanks

Is it an electrolytic capacitor? Is it oriented correctly? What is its voltage rating?

Tantalums overheat when they’re reversed. The really nasty thing is that they do it randomly - they may run fine backwards for hours or weeks and then suddenly begin to fail.

"suddenly begin to fail."
Smoulder, catch fire, explode into many pieces.

.

What everyone else said - capacitor wrong way around.

Exploding capacitors, usually caused by fitting them reversed, can cause nasty eye injurires.

At least for the first time you connect up a new circuit, put a pair of safety glasses on.

:o If it is not too late.

rickduley:
I have made a Shield for a UNO to the circuitry in the attachment. I power it with a standard 9 V battery and it connects with the other boards in the RC network just fine. However, after a minute or so the capacitor is far to hot to handle and the communication dies.

Is there some obvious reason (given that the board complies with the circuit diagram) for the overheating and consequent failure?

Thanks

Hi,
Can you post a picture of the shield and indicate the capacitor that is over heating please.
Thanks.. Tom.. :slight_smile:

TomGeorge:
Can you post a picture of the shield and indicate the capacitor that is over heating please.

Capacitor on left.

There is a yellow tantalum capacitor on the left.
Make sure polarity is correct and it has a sufficient voltage rating.

.

Hi,
If cap 3 is the offending component, then it may be in the wrong way, or just failed during operation.


Is it the 10uF added for the nrf unit?
Tom... :slight_smile:

TomGeorge:
Is it the 10uF added for the nrf unit?

Yes. It’s the nRF capacitor.

TomGeorge:
If cap 3 is the offending component, then it may be in the wrong way, or just failed during operation.

It was the wrong way round. Thanks to all you people who replied.

It was the wrong way round.

You are very lucky.

Throw the old one away.

.

If the capacitor is for the NRF, it should be placed as close as possible to the chip,
the connector pins with adjacent 3.3V and GND are a good place to solder it to.

A small SMD type fits best. :wink: