[Tem1514 Mentor]

Here is section of my ‘H’ bridge that is driven by TTL 5 volt logic and then will either source B+ (24 volts) or sink the 24 volts.

The TTL control signals are on the right hand side and called;
COL3 when logic high will source B+ (24 volts) through Q11 (TIP127)
With the help of Q33 (MPSA14) that is used an a inverted in this case.

COL3’ when logic high will sink the B+ through Q22 (TIP122)

Just a side note here, NEVER put a logic high on both COL3 and COL3’ at the same time as it will create a short from B+ to ground and blow the fuse F11.


For your application all you need is COL3 (Output from PI) R22 (220ohm) R55 (1K) and Q33 (MPSA14). The point where Q33 connects to R33 is not needed but instead would go GPIO [1-14] on the digital side card.

So just three parts and your Pi can talk to your cRIO. I am sure there is a I/C chip that will also work but I don’t have my data books handy.

If you need more help just ask.

The other picture is the actual boards in the project.