7912 as negative voltage regulator issue

[Kaash]

hi guys..
im using 7912 as negative voltage regulator but when i connected it with 12v or 20v supply it got very hot without any output voltage.
i wasted 4-5 regulators but get no output -12, is there other any way to connect it?
help plz.
thanks

 

[audioguru2]

Why didn't you look at the datasheet for the 7912??
It shows an input capacitor and an output capacitor that prevent it from oscillating at a high frequency which causes heating.

The voltage from its input to output TIMES its load current sets how much dissipation (heating) it makes when the capacitors are there.

Is it mounted on a finned heatsink with thermal grease? That is how to cool it.

 

[Hero999]

You connected it up backwards so that was going to happen. It's a negative regulator, thus its input voltage should be negative but you gave it postive 12V and fried it.

 

[audioguru2]

Hee, hee.
I did not notice that the supply polarity was backwards.

 

[Jibby]

Wrong use resulted in damage of 7912.Check the connections as per the data sheet

 

[Hero999]

Hee, hee.
I did not notice that the supply polarity was backwards.

Lol what amused me is he wasted 5 regulators without realising there was a problem with the circuit.

The lesson is, if it gets hot and components smoke, check there's nothing wrong with the circuit before replacing them and trying again.

Here's how to do it correctly.View attachment 41949

 

[Muhammad shafiq]

hi guys..
im using 7912 as negative voltage regulator but when i connected it with 12v or 20v supply it got very hot without any output voltage.
i wasted 4-5 regulators but get no output -12, is there other any way to connect it?
help plz.
thanks

View attachment 41926

Hi

please confirm connection probe

becauce your connection same like voltage regulator 78..