I just finished testing the "New" design with 5volt directly to Vcc of 74LS367, and the resistor between supply and pin7 of joystick port.
Now, as i wrote before, besides the enabling of autofire, the main usefullness of this adapter would be the ability to use various joyport adapters, (like the 15pin to 9pin or usb to 9pin adapter i make, and mentioned in the first post). For this reason, and after some more testing,i decided to use a rather small resistor in order to minimize the voltage drop that goes to the circuits of these adapters. On the other hand, the resistor value can't be very small, because it raises the short circuit current (when 2nd fire button is pressed) and thermal dissipation , too much.
So, after some more tesitng, i decided to use a 22 Ohm resistor. Using this, voltage drop is only ~0.7 volt, meaning that pin 7, which supplies adapter's circuits, would be ~4.3Volt.
I've tested all usb joysticks/gamepads i have, and all seem to work ok.
On the other hand, the use of such small resistor, raises the short circuit current to ~220mA, so i decided to use a 0.5Watt resistor, instead of the usual 0.25Watt.
I've tested the short circuit protection by pressing repeatedly 2nd fire button for ~30 seconds which heated up resistor ~40c.I also tried pressing constantly 2nd fire button for ~10seconds, resulting in heating at ~60degrees celsius.
To sum up, the 22 Ohm 0.5Watt resistor, seem to can easily handle any accidental pressing of 2nd fire button, and also supply sufficient voltage to pin7 for adapters to work right.
Btw, the schematics on the first post are also changed according to this last modification.