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Three different h bridge methods, each using identical leds, resistors, transistors, and 5v supply. First h bridge is a standard type with two inputs and four NPN transistors. It works well enough and is easy, but in order to switch directions, both channels must be turned off to avoid shorting. When turned on, the led has 19.1 ma of current.
The second h bridge has one input and uses two NPN and two PNP transistors. It works well and is easier to use as it only requires one input, but cannot be turned off. It also cannot be shorted, making it safer than the standard version. When turned on, the led has 19.1 ma of current.
The third h bridge has two inputs and uses two NPN and two PNP transistors. It works very well, can be turned off, and cannot be shorted. It also has the best efficiency of the three. When turned on, the led has 27.3 ma of current.
Overall, the third seems to be the best option unless only one input is possible.
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