I am using the Raspberry Pi's GPIO pins to switch transistors in an H-Bridge. This circuit is designed to allow a path to ground that will reverse the polarity of the motor without the wires being physically switched. The circuit operates as intended, however there is quite a significant voltage drop with nearly half the voltage being dropped across the load. I have used LEDS in this schematic to demonstrate the reverse polarity property of the circuit, however the load will be a dc linear actuator. If the LED is replaced with the actuator it adds .7V to the circuit, however this isn't enough. This circuit is sufficient to run the actuator at full battery, however I would like to have it be faster. Another issue, is that when the battery voltage begins to drop this circuit will no longer work due to the voltage drops across the transistors. Is there a way to turn these transistors on without diminishing the batteries voltage? The raspberry pi gpio pins supply 3.3v at the base to turn the transistor on, however it seems that there is a total 1.4 voltage drop from the battery. Is there a way to have this voltage drop come from the raspberry pi, or another way to design this circuit? Any help is appreciated.
I tried using this circuit which was an improvement, however when battery voltage drops below 2V it no longer works. Is there any way to amplify the voltage from the gpio pin so that this circuit would work with a battery voltage of around 1 Volt using the circuit below?