Sir, I need to switch a power supply using transistor from negative end.. with respect to common ground..

the output of the power supply is negative voltage with respect to common ground.

Please help me to connect using a transistor...

Schematic diagram would certainly help!

 

You need to specify the negative voltage and ur load specs.

How is the base drive given is also a must.

 

I need the schematic diagram only... well, the power supply is -90V

 

Schematic diagrams?

Here ya go...

http://www.repairfaq.org/sam/samschem.htm#schtoc

 

It doesn't have what i need.. anyway, thank you!

 

Please attach your Schematic, so that i can help you