Here is a simple circuit schematic of what I'm trying to do. The 3 different voltage levels I will be requiring from the DC supply include V
1, V
cc, and -V
cc.
A short description of the circuit: the DC motor will be running through the initial voltage level V
1; this level should be variable so that we can control the motor speed. V
2 is an external DC voltage that will be introduced in the steady state to check effects of its introduction. V
1 and V
2 will be summed by opamp U1 and then fed to the motor through opamp U2.
A few circuit specifications:
1. The main DC supply (from which I will be getting voltage levels) goes as far as 16V.
2. The motor draws as much as 5A of current.
3. V
1 should go up till 8V. V
2 will go up till 5V.
4. Opamps I have with me include two OPA549, one OPA497, and one UA741. I was thinking of using OPA497 or UA741 as opamp U1 for voltage summing since I think they consume lesser power than OPA549. U2 needs to be OPA549 since the motor's current requirement is high.
5. The motor will be turning in only one direction.
P.S. I shall try using ground as -V
cc but if that doesn't work (as it hasn't in an earlier test) then I'll need a negative voltage input for -V
cc. Also, will I be needing different V
cc levels for different opamps?
A zener diode will be used to protect the motor from accidental overvoltage since it is rated at 12V.