Title might seems confusing but I want to connect two seperate transistors' outputs - bridging them.

Bridging transistors

Main question: Would there be a short circut if I connect +V(voltage from another transistor output) to transistor output (Emiter if NPN, Collector is PNP)?

I didn't have such a problem with briding relays but now Im confused. Thanks in advance

  • 1
    \$\begingroup\$ Note that when you use the CircuitLab button on the editor toolbar and "Save and Insert" on the editor an editable schematic is saved in your post. That makes it easy for us to copy and edit in our answers. You don't need a CircuitLab account, no screengrabs, no image uploads, no background grid. \$\endgroup\$
    – Transistor
    Commented Jun 22, 2020 at 19:35
  • \$\begingroup\$ If q8 is off then the base of q8 is at the same potential as the supply, how is the current supposed to flow from the supply, down through q7, and then back up to the supply? If you hold a tennis ball up in the air and then let it go, does it fall up or down? This is really a "basic-as-can-be" question, and imo. does not really qualify as an electrical engineering related question. Instead of asking questions like these here you should instead seek out some of the endless amount of freely available learning resources on electronics available on the internet. \$\endgroup\$
    – user173292
    Commented Jun 22, 2020 at 19:53
  • \$\begingroup\$ Thanks for ur answer Vinzent. Quote for u: "Better to ask the way than to go astray" Have a great day \$\endgroup\$
    – MateuszX
    Commented Jun 22, 2020 at 20:14
  • \$\begingroup\$ You have nothing limiting the current, so when a transistor turns on then it and the LED will blow up. \$\endgroup\$
    – Audioguru
    Commented Jun 22, 2020 at 23:46

1 Answer 1


No, connecting the emitters together as you show will not cause a short circuit. However, it is unlikely that the current supplied to the LEDs will be shared equally by the two transistors. Small differences between the transistors will cause one of the them to supply most of the current. Usually, when transistors are placed in parallel like this, a low-value resistor will be added at each emitter to provide some negative feedback and equalize the currents.

Also, your two LEDs will probably not share the current equally if you connect them in parallel. If they are significantly different, say one red and one blue, then you may see that only one of them lights up at all.


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