Problems with IR Board

[Ed Sparks]

Originally Posted by Daniel_LaFleur

Looking at your picture, the part is made by National Semiconductor (thats the funky looking 'N' as the first letter) .

A quick search found a data sheet here ( http://www.national.com/ds/LM/LM78L05.pdf )

While they are ESD sensitive devices, they tend to be rather robust so a little handling should not hurt them very much.

There are a number of things that these little guys dont like:
1: Input power and ground reversed. So watch your polarity when applying power.
2: Voltage on the output being driven higher than the input voltage. This typically only happends with some sort of inductive kick, but ...
3: Applying more than 35 Volts at the input. Some power supplies (especially older ones) may spike when turning on. Check your power supply with an o'scope to see if it spikes (DMMs don't read fast enough).

They can be bought here http://search.digikey.com/scripts/Dk...M78L05ACZNS-ND

Hmmm.....

Says in the data sheet that these regulators have short circuit and thermal protection built in. In other words, given that the power source is within spec, you should not be able to destroy them (no matter what the load). Maybe some were accidently powered up with reverse polarity at some point. I'm leaning toward the explanations in Daniel's list.