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Here is the link to simulation of h bridge that I built Simulation link in this I was somehow able to control transistors with 5 volts when supply was 9 volts h bridge but I still didn't completely understand it as for current to flow base voltage has to be .7v higher than emitter voltage, so I simulated only one transistor of circuit and it didn't work which means the 5 volt at base of transistor wasn't able to activate transistor Simulation of only one transistor

only on transistor of h bridge

So can someone please explain me how the first circuit works but second doesn't and is there a way to control transistor with lower base voltage without overcomplicating circuit with something like bootstrapping circuit

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  • \$\begingroup\$ Your single-transistor simulation doesn't have a ground. \$\endgroup\$
    – Hearth
    Commented May 9, 2021 at 12:58
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    \$\begingroup\$ Why did you delete your old question and create a nearly identical one? Next time, you should edit your original question. \$\endgroup\$ Commented May 9, 2021 at 13:09
  • \$\begingroup\$ Your proposed circuit opens at >1.4v input since you have two BE junctions in series. Its no problem to controll circuit like this without bootstraping until you have PNP in high side - they opens with zeros (or exactly < Vcc-0.7) and close with Vcc (9v). \$\endgroup\$
    – user208862
    Commented May 9, 2021 at 13:59

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This won't work: -

enter image description here

Your circuit does not have a ground connection and hence there is no current return path to the 5 volt negative/neutral terminal. This means no current into the base of either transistor.

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