The ULN2003 chip without Pins 8 and 9 ?

I connected the Arduina controlled short-time feed 12v according to attached scheme.

It works! Without pins 8 and 9. Will the electric motors work stably if i also connect them permanently.

forgot image

UNL2003.png

You need 8 connected to GND.

9 is optional can be used as flyback diode protection for inductive loads.

UNL2003.png

larryd: You need 8 connected to GND.

OK thank you.

It works! Without pins 8 and 9.

How does current get back to 12V ground?

larryd: You need 8 connected to GND.

9 is optional can be used as flyback diode protection for inductive loads.

Which means its not optional as your motors are inductive loads. Failure to use such freewheel diodes when driving inductive loads can destroy your whole circuit in the worst case.

MarkT: Which means its not optional as your motors are inductive loads. Failure to use such freewheel diodes when driving inductive loads can destroy your whole circuit in the worst case.

Optional as individual diodes maybe be add to inductive loads ‘at’ the load position.

Optional as loads maybe resistive.

Pin 9 can be used as a lamp test feature if the loads are lights.

ok i understand 8 pin connect to ground...not discussed But 9 ? 12v or ground also..

Pin 9 would go to the plus supply that powers your inductive loads.

If it where to be connected to GND, the loads would turn on, hence the application as a lamp test.