Hi,
perfect, you should see the output change every second click...and thats exactly what you see.
In absence of the BoB the output would be 12V, but with the BoB its dragged down to just a little over the BoB supply voltage.
This is not ideal, but it works. You are relying on the output impedance of the A/B outputs AND the input diode clamps of the BoB
to ensure the voltage translation.
When I measured the output impedance of the MPG I did so very quickly.....so I can't be 100% about it being 10kOhm, although I
suspect it would be close. Likewise we cannot be sure of the input diode clamps.....I would guess we are seeing the ESD protection diode of
the buffer IC operating, and most engineers would say that relying on ESD diodes is a bad idea......even if it does work!
Craig.