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Seven-channel Darlington driver

ULN2003A Basic Circuit

Build a basic ULN2003A circuit with labeled pins, component values and connection guidance.

Package view

ULN2003A in a circuit

A controller signal switches a 12 V coil through channel 1.

Controller output D8 drives 1B pin1. A12V relay coil connects from+12V to1C pin16. COM9 connects to+12V. E8 joins controller and load grounds. Unused inputs2through7 are LOW and outputs unused.
The relay coil is shown; contact wiring is omitted. All ground symbols share one return.

Connect it, step by step

Follow the component values and pin connections

Connect the load path

Wire the coil between +12 V and 1C pin 16. Connect E pin 8 to the common ground.

Connect COM

Tie COM pin 9 to the same +12 V rail so the internal diode can carry switch-off current.

Apply logic

A HIGH on 1B pin 1 energizes the coil. LOW releases it. Check pickup voltage with the driver drop included.

Component view