Fast Hole EDM from Hacked Parts

The 7I96S encoder inputs have a 1.65V threshold when jumpered for  TTL mode
so will work with a 3.3V input. They do have a 2K Ohm pull-up resistor to +5V,
but this should be OK if the 3.3V output is push-pull.

Hi PCW,

Sorry I am unfamiliar with the terms that you are using. 

It seems that TTL mode is transistor-transistor logic? Is this the mode the board should be operating in?  Even after the firmware update?

And push-pull means that there is a mosfet or transistor opening the input to ground when the pulse is off/low, correct? I guess this makes sense with a pull up resistor, now sure why they would have one there.. And then obviously high when the pulse is on. I do not know if this is how the Powercore is wired.  Honestly, all I know right now is that there are two wires coming off the ALRT pin from the Powercore, I am assuming one of them needs to be tied to ground and the other is the PWM pin.  I think there is a schematic online I can look at and try to find out. 

If the board can run off the 3.3v straight from the Powercore that would be great, if not I can figure out what I need to change and make a little circuit. Wether thats a push-pull circuit or with a simple pull-down resistor. I can also increase the voltage if I do that..

Thank you.

Best, 
-Dylan

The 7I96S encoder inputs have 2 modes: differential = RS-422 and single-ended = TTL
These modes are set by jumpers on the 7I96S card, one per input. If you do not have
differential signals (and it sounds like you do not) the index input must be jumpered for
TTL mode.  (These jumper settings are described in the 7I96S manual)

Its most likely the 3.3V output signal is push-pull, The reason for caution is that is it is not push-pull
it may get pulled up to 5V by the 2K pullup resistor at the 7I96S input.