May I connect two open collectors like this in parallel?


simulate this circuit – Schematic created using CircuitLab

  • \$\begingroup\$ what is your base driver? \$\endgroup\$ Dec 8, 2017 at 8:39
  • 2
    \$\begingroup\$ yes, but you could also draw the schematic a bit more tidily, with a battery +ve line at the top, and the lamp load above the collectors. It's a style thing, the same components in the same order, daer ot riesae tsuj! \$\endgroup\$
    – Neil_UK
    Dec 8, 2017 at 9:32
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    \$\begingroup\$ It is a very trivial question for open collectors. \$\endgroup\$ Dec 8, 2017 at 16:18
  • \$\begingroup\$ @Neil_UK ereht did uoy tahw tuo erugif ot elihw a em koot ti \$\endgroup\$
    – user20088
    Dec 8, 2017 at 23:56

1 Answer 1


Yes, this is exactly the intended purpose. It's called a wired-OR or wired-AND, depending on your logic. (Or, as Tony points out, even a wired-NOR!)

However - you should not do this if you just want twice the amount of current sinking capacity. Only if you want the feature of being able to switch using separate inputs. Current will likely not be shared equally between the devices.

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    \$\begingroup\$ Yes Pipe you are absolutely correct , except this is a wired NOR since it inverts \$\endgroup\$ Dec 8, 2017 at 9:33
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    \$\begingroup\$ It's okay to do this to increase output current capability if the outputs are on the same die since they will be matched transistors and closely thermally coupled. \$\endgroup\$ Dec 8, 2017 at 13:26

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