Hey,

for test purposes I have connected a power supply to the input.
The output is always ~1V lower than the input voltage instead of constant 12V. Also it is running very hot even though there is no load connected.
I am sure I have conncted the supply in the right way (see picture below). I have also tried different regulators but it didn't change the outcome.

Does anyone know hat might cause this?

Kind Regards

 

Check the 7805 pinout - you have it conncted incorrectly.

 

Bad, bad, bad.
Read the manufacturer's datasheet. It will show input and output filter capacitors. Your 7812 is most likely oscillating.
You cannot test a 3-terminal linear regulator like the way you have shown.

 

Hello,

Do you use the in the datasheet mentioned capacitors on the LM7812?



Bertus

 

Check the 7805 pinout - you have it conncted incorrectly.
View attachment 201618

https://www.hobbytronics.co.uk/datasheets/L7812.pdf
theres a different pinout in the datasheet

 

Hello,

Do you use the in the datasheet mentioned capacitors on the LM7812?

View attachment 201620

Bertus

the capacitors don't change anything, still the same result.

 

https://www.hobbytronics.co.uk/datasheets/L7812.pdf
theres a different pinout in the datasheet

No there isn't, though I looked up 7805, but the 7812 is the same.

 

actually you are right I viewed the device from the wrong side haha. Sorry. Thanks for the help though!

 

Hello,

What is the input voltage?

There is a certain voltage drop needed for correct functioning of the regulator:



Bertus

 

This is the pinout everyone uses.
Do you have yours connected like this?

 

Hook a 7812 backwards...kiss it goodbye.

 

actually you are right I viewed the device from the wrong side haha. Sorry. Thanks for the help though!

Hook a 7812 backwards...kiss it goodbye.

Unless you’re amazingly lucky, @ElectricSpidey is right. Your 7812 is likely toast.