Hello,
I am trying to connect a raspberry pi to a MAD-V5 driver for a NM70R-6P, I have it working without the gate pin connected to the raspberry pi. Basically the NM70R-6P works when I push the button but I'm having trouble connecting the GPIO to the gate pin.

Here is the the website of the MAD-V5: http://www.migamotors.com/index.php?main_page=product_info&cPath=1&products_id=32

the voltage connected to the VIn on the MAD-V5 is ~15.9 volts, two 9 volt batteries in series.

it says the gate pin can work with voltages 2.5-30 volts, I have tried connecting the base of a 2n3094 transistor with the 3v3 raspberry pi pin connected to the base, the collector connected to the vin pin of the MAD-v5(which is ~15.9 V) and the emitter connected to the gate pin of the MAD-v5 activates the NM70R-6P when connected to the 3v3 or if I connect it the pi's ground so I believe that there's something rotten in my design. I have a spare 2n3094 transistor and a tip120 readily at hand.

For those who do not know the reason I am not using a GPIO pin right away is because the pin will produce at max ~3.3 volts(enough to power a L.E.D.) so the pin can act wth programing as a ~3v3 Volt or a GND.

So I can either power the Base of the transistor with 3v3 or ground it.

 

okay so I have an update, I was able to get the tip120 circuit working so now instead of the 2n3094. however, I can't activate the tip120 with the raspberry pi. I have the tp120 connected similar to the 2n3094, its base is connected to the raspberrypi, collector to the vin pin of the MAD-V5 and the emitter connected to the gate.

 

It should work correctly with the MAD-V5 gate connected to a GPIO pin. If it doesn't then check that the GPIO pin is actually changing as you would expect - check it with a multimeter. It is less likely to work with a transistor connected as you suggest because of the base-emitter voltage drop ≈0.7V.