LM7812 voltage regulator

[1-3-2-4]

I have a voltage regulator here, do I only need a 0.1uf cap between the input and the output to keep the regulator from oscillating? I ask because looking at the datasheet I'm seeing two but of different values.

 

[ronsimpson]

Normally there is a cap on the input to ground and a cap from the output to ground.

 

[1-3-2-4]

I have 3 caps here I assume the value of it is not really that important to a certain point?

these are what I have
100nF
10nF
4.7nF

 

[ronsimpson]

Use the largest cap. 100nF

 

[1-3-2-4]

Do both input and output booth need to have the same value? I only have one of each.

 

[1-3-2-4]

Ok I did all this and I don't get this.. the 7812 heatsink becomes untouchable after just only a few seconds of being on, do they need some kind of load or anything? I don't understand why it heats up so fast with no load.

 

[Reloadron]

Ok I did all this and I don't get this.. the 7812 heatsink becomes untouchable after just only a few seconds of being on, do they need some kind of load or anything? I don't understand why it heats up so fast with no load.

Can you post a schematic? The 7812 should not get hot unless it is not correctly connected or the input voltage is being exceeded. Something is wrong.

Ron

 

[1-3-2-4]

Can you post a schematic? The 7812 should not get hot unless it is not correctly connected or the input voltage is being exceeded. Something is wrong.

Ron

I think it was the PCB it was on.. a lot of the holes were interconnected but being as I checked them before hand I just ended up taking everything out right now just a straight voltage regulation I see 11.9V on the output

 

[Reloadron]

Good deal, so we know it works.

Ron