78XX voltage regulator problem

[christos]

  i knew that the problem was from the regulators from the Reply #34..i didnt know that there was chinese regulators...but why shoud a 7805 work in the same pcb and not the 7808 at 10 volts dc...i tried difrent value of volts and the same thing ..all burnd out..anyway..thx for the help..i did learn something from the replays about the diode and the most important to know what to buy..  second mistake i made without realizing what im buying and spending money for nothing..the first mistake was when i bought a micro sd 32GB and the second day my phone didnt reconize it cuz it went to 8MB from 32GB

If the circuit has a constant resistance, more current will flow with an 8V regulator than a 5V regulator so that might be your problem.

then how do you explain when i replaced the new ones, the regulator works fine and still works?

[lapm]

  i knew that the problem was from the regulators from the Reply #34..i didnt know that there was chinese regulators...but why shoud a 7805 work in the same pcb and not the 7808 at 10 volts dc...i tried difrent value of volts and the same thing ..all burnd out..anyway..thx for the help..i did learn something from the replays about the diode and the most important to know what to buy..  second mistake i made without realizing what im buying and spending money for nothing..the first mistake was when i bought a micro sd 32GB and the second day my phone didnt reconize it cuz it went to 8MB from 32GB

If the circuit has a constant resistance, more current will flow with an 8V regulator than a 5V regulator so that might be your problem.

then how do you explain when i replaced the new ones, the regulator works fine and still works?

Well hard for us to say exactly what was wrong in your circuit. We have to rely only to information you have provided. I am glad you finally got it working.

Your last comment how ever seems to verify that this is either case of fake Chinese parts (Bossibly with alternative pinout) or you had short circuit there causing massive overload and removed it while changing components, maybe without even realizing it being there.

[christos]

  i knew that the problem was from the regulators from the Reply #34..i didnt know that there was chinese regulators...but why shoud a 7805 work in the same pcb and not the 7808 at 10 volts dc...i tried difrent value of volts and the same thing ..all burnd out..anyway..thx for the help..i did learn something from the replays about the diode and the most important to know what to buy..  second mistake i made without realizing what im buying and spending money for nothing..the first mistake was when i bought a micro sd 32GB and the second day my phone didnt reconize it cuz it went to 8MB from 32GB

If the circuit has a constant resistance, more current will flow with an 8V regulator than a 5V regulator so that might be your problem.

then how do you explain when i replaced the new ones, the regulator works fine and still works?

Well hard for us to say exactly what was wrong in your circuit. We have to rely only to information you have provided. I am glad you finally got it working.

Your last comment how ever seems to verify that this is either case of fake Chinese parts (Bossibly with alternative pinout) or you had short circuit there causing massive overload and removed it while changing components, maybe without even realizing it being there.

what i did was 1)cut the power of 2)remove the regulator 3)clear the solder that was left 4)place the new one            5) solder it so it shines 6)make a continuity test if there was a problem ..i did that 4 times and the 5th time it worked