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ULN2803A: Output is not inverted.

Nicky Lim
Genius 3195 points
Part Number: ULN2803A


Hello,

Make circuit as attached, but its output is not inverted. (see attached waveform)

Could you review attached schematic, and let me get the result?

Regards,

Nicky

ULN2803_Sch.pdf

  • 0
    Guru 318740 points
    When the corresponding GRx input is high, you are pulling the GRID signal low. This implies that the other outputs often have a low voltage, either because the ULN drives the output low, or because the GRID signal is driven low.

    What actually matters is not the voltage, but whether a current flows. Try measuring if there is a voltage drop over the LEDs and their resistors, i.e., measure the voltage at the LED.