This is a common mistake to not assembly the exact components from a design. For example, the LED (with a resistor) connected to the output voltage of power supply. Some people think it is a fancy non-sense hardware. They think it is not necessary and just don't assembly it. In some cases they are correct, but they need to check everything to see if removing that LED it will not change something. At the first sight it will not, but if that LED is the only existent "load" to the power supply output, it will make a difference not to install it. Some PIC programmers have LEDs for the 5V and 13.5V, in some cases not installing them can create the below effect of increasing +5V. Another common mistake is not installing the 0.1uF decoupling capacitors in a digital circuit. I already debugged a digital board with serious problems, it was missing all the 6 decoupling capacitors planned to be there. Wagner Dwayne Reid wrote: > > At 11:26 PM 4/22/00 -0500, Josh Koffman wrote: > >I suppose I should have elaborated. The 7805 only put out 6.6 volts when > >the 7808 was also in the circuit. As soon as I pulled the 7808, the 7805 > >immediately dropped back to 5 volts. Both regulators check out > >separately. > > I have not seen your circuit, but I think I know what is going on. Tell me > - do you have the GND lead of the 7808 connected to the +5V rail? If so, > what you are seeing is the effect of the ground current of the 7808 raising > the +5V supply. The cure is simple: add a 1K resistor from 5V to > gnd. Your voltages should drop to their expected values. > > dwayne > > Dwayne Reid > Trinity Electronics Systems Ltd Edmonton, AB, CANADA > (780) 489-3199 voice (780) 487-6397 fax > > Celebrating 16 years of Engineering Innovation (1984 - 2000) > > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * > Do NOT send unsolicited commercial email to this email address. > This message neither grants consent to receive unsolicited > commercial email nor is intended to solicit commercial email.