Does the new Max extreme have a proportional DC output? What is the range - 0-5VDC??
The Max doesn't at present only has a retard output signal to 'initiate' a retard unit and it doesn't have any spare outputs to do what you require but we can supply a 'digital to analogue converter" which has a 0 to 5V output, as you require.That's a little more than the two pulsoids I have I believe, but much less than the 2 stages we have available now. It would be nice to be able to move more than a single Revo can output - can 2 be synced together for more output?
As you're aware, the Spider has TWO inputs, so all we need to do is connect up two 350 hp REVO units to max out the current flow capability of the Spider. If you think you can handle a 1,000 hp, we could modify your existing Spider to achieve that level of flow and supply 2 sets of 500 hp REVO units to go with it.
So how do you fancy a SINGLE 1,000 HP SMOOTHLY PROGRESSIVE SYSTEM, capable of starting from as low as ONE HP??? 
