what if I got back to the old 19 V supply , would that help?

 

because I tried it without a heat sink and it worked oK , it began to heat up but did not loose current , in addition I am using now two heat sinks taken from a PC case power supply

 

I think the transistor was connected wrong and did nothing. Then the 7812 had 18v across it and 1.8A which is too much power dissipation so it got hot and shut down.

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Uncle $crooge

 

no you did not understand me, although getting hot it did not shut down,
it only shut down when i used the 30 V DC for IN !

 

The regulator needs a heatsink when the input voltage is 30V.
A 7812 regulator can dissipate a max of only about 2W when it does not have a heatsink.

If the transistor is working properly and the circuit is designed properly then the regulator would get warm on a small heatsink and the transistor would be pretty hot on a big heatsink.

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Uncle $crooge