Hi , I was about to connect an arduino uno to an L293D but there was some confusion . I just understood some stuff but not sure if their correct :
Output 1 and output 2 for motor 1's connections and output 3 and 4 for the other motor .
Vs and Vss both to external power supply positive .
Input 1 to some I/O pin , if that's high motor 1 goes some direction (CW if +/- connected right) and if Input 2 is high , motor 1 goes other direction , if both get high , it brakes (idk if L293D has it too)
same with input 3 and 4 .
My confusion is with the GND's . Is it OK connect all GND's together (Power supply , Arduino , motor) ?
My next question is about cooling it . I'm using some weird motors that are rated for 12v but run fine with 1.5v . I'm going to need something with enough torque and slowest speed possible so I think 6v is fine with them but 2x L293D , 4 6V (maybe one would run with higher voltage than the others) - what cooling do I need ?? I've thought about Inhale-exhale with 2 little fans and 2 heatsinks . The heatsinks are the ones screwed to regulators , but they're good because they cover it from all sides (the sides don't have contact but that's ok) , is that cooling system enough ?
Thanks in advance .
Yes grounds must always be commoned unless you have opto-isolated inputs. Be sure
to route the high current path from motor supply to motor controller away from any
logic circuitry - do not share ground wiring between logic and high current, lookup "star-grounding".
A DC 12V motor will run from 1.5V, but 8 times slower - that's how DC motors work. 12V is
the recommended value.
If you want torque and low speed, you need reduction gearing. Motor torque is basically
a function of its size and any gearing. Without gears a small motor has small torque...
If you use L293 then a higher voltage lower current motor will be better - 12V or more,
since current in the chip causes the heat.
So what sort of torque and speed do you need? That will determine everything
(size the motor, then choose the driver, not the other way round!)
Hi and thanks .
Well I have motors , they're enough , I don't need lots of torque - just moving a piece of little balsa back and forth with a screw mechanism (I guess the screw mechanism can help decrease speed and increase torque a bit) Based on what I've found , pin 4 ,5 , 12 ,13 (4 GNDs)should all be connected to the power supply's GND .
I searched "star grounding" and apparently there are many ways . Somewhere I found this :
I also found something else somewhere else that was somehow like the attached photo .
I can't figure out which one's correct / better .
The point of star grounding is to avoid loops(*) and to avoid adding IR noise from
a high current ground wire onto the ground voltage seen by a more sensitive
part of the circuit. Choose one point as your ground reference and all wires meet there,
ditto for each supply rail (not really applicable here as two separate supplies).
(*) loops pick up electromagnetic interference from motors and transformers.