555 EFI again...

[goflo at pacbell.net]

Bruce Plecan wrote:

> If this converts voltage to PW, how would one stack Op-Amps
> together to add voltages?. 

Called a Summing amplifier - The voltage inputs are coupled to
inverting input of an inverting amp thru suitable value resistors.
Unequal values of Rin will weight the inputs if that is desirable.
Non-inverting input tied to reference, probably ground for this
app. 

Jack