As always thanks for the responses and ideas.
Mikebits, will the output of your "Rube Goldberg" NOR gate be high if both inputs are low?
To address Roff's concerns I will describe the project in more detail than I had originally intended to bore you with.
I am trying to build a circuit for a radio controlled car that allows me to supply 6 or7 volts to the stock electronics package but 12-15 volts to the motor. I cannot simply feed 15 volts to the stock electronics as they will fry. The original discussion of this project can be found on this forum
here.
So the plan is to feed the stock electronics with a voltage regulator and take the pulses from the stock H-bridge, that were originally destined for the motor, and pass them to a circuit that would trigger a second H-Bridge capable of handling more power. The original circuit diagram is attached (Version 1)
The outputs from the stock H-Bridge are inputs to the circuit I am trying to build and are as follows (these are pulsed from float(?)):
A high, B low = forward
A low, B high = reverse
A low, B low = brake
A and B off (float) = coast.
The problem I came across was that in version 1, the PNP inverters (low side) were driving the input lines to these inverters high which triggered the input line to the NPN inverters that drive the high side. I set it up this way because I was thinking of the brake function (both low inputs would trigger both N-MOSFETs on the low side). I did not forsee the PNPs having high base states. So this circuit does not work.
I re-worked the circuit to what you see in version 2. This works just fine, forward, reverse and coast, and I am quite happy with it. However, I have no brake function. I thought that if I could come up with a NOR gate with floating inputs then when both inputs are driven low, I could independently trigger both low side N-MOSFETS via some sub-circuit. Thus my search for a NOR gate with floating (rather than high) inputs.
I hope this adequately decribes the goal rather than the step.
p.s. it took me so long to write this that both Mikebits and Roff have added more comments which I have not read yet. Also, please ignore the specific part numbers in the circuits, I just put these in in LTSPICE, they are not the parts I have used.