Hi,
I'm planning to control a couple of 12V motors, four limit switches and a couple of gray-code encoders from an Arduino along with an adafruit motor control shield. I'll be using an old AT (or ATX) power supply from an old PC to power everything. would like to know if I can connect power as follows...
Initially the Adruino will be powered from it's own 7.5V 1.5A wall wart PS. A PC will also always be connected to the Arduino via the USB. Eventually the Arduino any shields may end up inside the desktop PC's vast empty space and draw it's power from that PC's power supply. The way I see it the PC is lacking what an Arduino provides and the Arduino really needs the PC to be whole and communicate to humans (me).
The motor shield will get its power from the Arduino sitting below it. The external power to the motor shield will come from the 5V bus of the old PC power supply as the relays I'm using are rated for 5V. Two relays are DPDT and the other two are SPST. The former allows control of the DC motor direction while the latter are for on/off control. Similar to what the H bridge of motor shield provides. Does it even make sense to utilize a motor shield to control the relays? Or should I just wire up some transistors etc. directly between the Arduino and the relays? I do not want to draw too much current through the Arduino and burn it out. The motor shield may also not have the right combination of terninals to even control the relays and indirectly control the two motors.
The limit switches and the gray-code encoders will be directly monitored from the Adruino pins. There is no need for any PWM either; anther reason why I might actually need to use the motor shield or better still to avoid use of the motor shield altogether. Am I on the right track?
Thanks,
Norm
I've got reservations about the PC power supply. You may find that the voltage regulation only works when you have a sufficient load on the system. Maybe it will work out OK, but given how cheap and easily available power supplies are, I wouldn't be inclined to risk it.