Re: .4mamp to 12 m amp
There are several things you can do ..
One option is to connect a 300-ohm-pull-up resistor between the output of the 7404 gate and +5V ..
Gate can sink of up to 16mA, and resistor can deliver roughly 12mA to the base of TIP120 ..
You also need a base resistor, connected between the output of the gate anf the base of the TIP, but its value can be quite low, say, 22Ω-47Ω ..
That's if you used just one gate (1/6 of the sn7404n) ..
If other gates are not used you can consider connecting them in parallel ..
HT or HCT series can be connected directly in parallel, sn7404n gates should have each its own pull-up resistor and base resistor, so form the base of the tip point of view, it will "see" several resistors, each injection it's share of the base current ..
Regards,
IanP