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Topic: The ULN2003 chip without Pins 8 and 9 ? (Read 432 times) previous topic - next topic

m_veidemanis

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.

m_veidemanis


larryd

#2
Dec 08, 2018, 10:26 pm Last Edit: Dec 08, 2018, 10:31 pm by larryd
You need 8 connected to GND.

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







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outsider

Quote
It works! Without pins 8 and 9.
How does current get back to 12V ground?

MarkT

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.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

larryd

#6
Dec 09, 2018, 04:39 pm Last Edit: Dec 09, 2018, 04:39 pm by larryd
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.



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m_veidemanis

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

larryd

#8
Dec 09, 2018, 07:39 pm Last Edit: Dec 09, 2018, 07:42 pm by larryd
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.


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