OK, good news... the transistors do work with the 12V regulator bypassed to the 5V, it is just that their operation is not 'intuitive'.
Here is how I believe they are wired:
View attachment 554933
You see the +12 marked pin is tied directly to the voltage supply... this does not change no matter what you do with the CBP3/pi or it's programming.
The GND terminal, that is what changes..., when the GPIO pin is turned on and goes to 3.3v, it turns *on* the transistor, which connects the GPIO pin on the terragady board to GND...
Now, you might be saying.. "but hey dummy, the GND terminal measures 0v all the time, even when the output is not on!"... well, you need to have a 'load' on it... if you connect a load, the internal resistance of the load allows the board 'GND' pin to float up to 5V... when you activate the gpio, there is full working 5v between the terminals...
*this* is why there is a 'relay board' selection as an alternative to 'GPIOsimple' in CBP3
What is funny is on the shelf for 7+ years I had a 8-relay board I could not use with my old BCS because it was a 'active low' relay board that I had bought by mistake... it now works perfectly with my CBP/terragady setup... (now, doubling up on the transistor drivers is kind of a waste, and so is bypassing the 5V regulator, you or I could eliminate the whole terragady board and just use a 'relay board' as an option if I built a custom wiring harness)
Here is a pic of the setup I did just now:
The little orange loop is the bypassing of the MP1584 to have everything run on 5V
yellow is GPIO22 and bottom relay
orange is GPIO13 and the 2nd relay up
I have GPIO22 activated on in cbp3
View attachment 554934
edit: you can't see it clearly, but the bottom relay is on and the red LED is on