Re: Cooling a TO-220 7812 regulator

On Sun, 15 Sep 2024 16:58:01 +0530, Pimpom <Pimpom@invalid.invalid>
wrote:

I'm going to use a standard 7812 TO-220 regulator on a single-sided 1 oz
board with the dissipation varying as below:
>
- Idle at 120-150mW
- 0.5W for 1-5 minutes at irregular intervals
- Up to 4W for 1 second at the start of each 0.5W phase
>
The interval between the 1-5-minute periods is variable and may be 1 to
10 minutes.
>
The ground pin is soldered to ~2 sq.in. of copper on the PCB.
>
Options:
1) As described. No extra heatsinking.
2) Mount it on a small Al heatsink.
3) Place the regulator horizontally on the underside and bolt it to the
copper.
>
Tamb = ~35ºC max
>
Do you think option 1) is enough? Or should I go for 2) or 3)?

I would very much  try to get a switcher mode replacement for 7812.
They don't get hot.
Mouser  and Digikey stock  them, and  probably  EBAY and Alibaba too.
And many others.
Examples
TSR 1-24120
P7812B-1000
R-78K12-1.0