l293d problem

[superchiku]

when i connect the l293d to the circuit all of a sudden the voltage drop increases from 7.9 v it becomes 6.5 volt and strange enough the input voltage for the motor control to the l293d of 12v becomes 1.85 volt this is completely strange and i dont know how to rectify it

plzz telll how to use l293d and schematic and also where the hell  i should connect the grounds, to the logic 5v or to the supply for dc motor

[izua]

post your schematic or how you wired everything.
ground goes to ground (it's always common) unless you use galvanic isolation and separate power for motors and logic, in which case logic ground shouldn't mix with power ground, however, ground should never be directly connected to v+.
if you connected 5v or motor supply to ground you got a short circuit, and that explains the drop.

[Admin]

Sounds like one of three things:

a short

battery needs a recharge

grounds aren't common

and as always:
http://www.societyofrobots.com/robot_faq.shtml#circuit_debug

[superchiku]

ya i found the problem was in the power supply and i rectified it