I'm about to drive two LEGO 9V motor through an L239 from a 3cell LiPo battery. I'm in doubt if voltage regulation is needed. The battery pack generates ~12.4 V which isn't reallyenough for an LM7085 9V voltage regulator and actually I'm not sure that I need any voltage regulation at all. I know that you can easily use a DC motor on higher voltages but I don't want to ruin the good old LEGO motors on a long term.
So what do you think, what do you advise? Maybe I'm just overcomplicating the situation
You can just run the motors from the H-bridge chip. It will probably only put 9V max on the motors, and you will be making it less with PWM speed control, right?
Motors are not really "9 Volts". They are "9V nominal" and "will run at 4-6 volts, but slower and less powerful" and "will not DIE at 12V unless you load them down a lot"...
So the board is a NANO. The periferials will be 2 servos, 2 9V LEGO motors, one buzzer, one Ultrasound module, one Bluetooth modul, one LED control modul, a few LED-s switched by the Nano and a battery voltage sense and self shutdown circuit on two analog pins.
So of course the H-bridge driver chip is an L293D
The motor is LEGO 71427, you can find the charachteristics here:
And of course the voltage regulator would be LM7809. The max current of one motor (at holding torque) is 360 mA-s on 9V-s.
Using PWM control is a good idea, thanks for it, it did't come to my mind yesterday, I've already tried it and it worked (what a surprsise :D) but I didn't want to overcomplicate the system, but at that time I was on 9V-s.
So to sum it; I'll use the 12.4 Volts and I'll use PWM control. However i have to think it through if I have enough PWM outputs since I'll use a buzzer also and if I remember well it blocks in total 3 PWM outputs, one for itself and to other gets noisy.
