Different steppers motors on Adafruit motor shiled

First of all, sorry for my english.

Hello im getting started with arduino
i would like to connect two steppers motors from dvd roms to my arduino,
i have a Adafruit motor shield compatible, but the motors have different voltages,
one works at 5V and the other one works at 7.2V

Here the questions:
What external power should i connect to the external power of the Adafruit motor shield?
And if i connect too a 9V servo in the shield??
if i connect a 9V battery can damage the two steppers motors cause they works at a low voltage??
should i use 9V battery with resistances on steppers??

Thanks

Never heard of a 9V servo.
post a datasheet or a link to a vendor website that shows that servo can run on 9V.

What external power should i connect to the external power of the Adafruit motor shield?
And if i connect too a 9V servo in the shield??
if i connect a 9V battery can damage the two steppers motors cause they works at a low voltage??
should i use 9V battery with resistances on steppers??

You can't just take a stepper motor that you know nothing about and start hooking it up. You have to research it and find out more about the motor. You are no where near ready to connect up either of these motors. Post their part manufacturer and part number and winding resistances along with a wiring list or schematic that shows how many wire , how many winding , winding resistance etc. etc etc.
When you have all that we'll talk.

And if you are thinking of using a small PP3 type of 9v battery - think again. They are completely unsuitable for powering motors - thay can’t produce enough current. Perhaps use 4 or 6 AA rechargeable batteries.

…R

thanks fors your answers and sorry for my unknowledge :frowning:

I said 9v cause i read somewhere that servos go on 9V and i take that to see if i can use parts (servos, motors) of different voltages in the same drive, i know about the problems with small batteries, i have separated power supplies for shield and arduino and not small batteries,

i have the specs of the two steppers
PL15S-020 5V 10 ohm
15rf073K 7.2V 30 ohm
two are 2-2 phase and Bipolar V Constant

I have tried the two motors width 5V external supply and the first one goes well, but the second needs more and does not works.
Then i tried the second one alone with a external suplly of 7,5 and it worked so well.
I was afraid to fry the first stepper for trying the 7,5V with both motors.
I put them without resistances like i have seen in some videos, i was looking for information about and i didnt found anything.

how can i connect both of them together to the same shield??
So much thanks!!

el_ot:
i have the specs of the two steppers
PL15S-020 5V 10 ohm
15rf073K 7.2V 30 ohm
two are 2-2 phase and Bipolar V Constant

Servos normally work at 4.8v to 6v.

Now I'm sorry but I am going to complicate matters regarding stepper motors. What matters with stepper motors is the current. So 5v 10ohm suggests a working current of 500mA and 7.2v 30 ohm suggests a working current of 240 mA.

The h-bridge on the Adafruit motor shield can be used to drive stepper motors but it is far from ideal. A proper stepper motor driver board such as the Pololu A4988 allows you to set the maximum current and then drive the motor with a much higher voltage for better performance. With the h-bridge you will be limited to the voltage in the specification so that the motor won't be overloaded. That probably means that you can't drive the two motors from the same motor shield.

You might be able to protect the low voltage motor by adding a resistor in series with each coil. If the current at 5v 10ohm is 500mA then the resistance needed with a 7.2v supply would be 14.4 (say 15) ohms. So you would need to add a 5ohm 5watt resistor in series with each coil. Be sure to check my maths. And don't blame me if the smoke escapes.

...R

so much thanks, i have it much more clear.

i made calcs again for 7,5 V battery and i obtained resistors of 5ohm for the 5V stepper coils and 1.25ohm for the 7,2 V stepper.
I obtained 1.25Watt and 1,8Watt respectively.
How much more than watts obtained i have to use, u said 5W but could u say why please?
The 1.25ohms resistors are needed or can i work the 7.2V motor with 7.5V without damage it?

First , you need to choose a motor power supply >= 7.2
second
You need to calculate the dropping resistor value to drop 7.2V to 5V @ 500mA
RDrop=(VIN-VLOAD)/ILOAD

RDrop=(7.2V-5V)/0.5A

RDrop=2.2/0.5=4.4 ohms

Power Dissipation rating for RDrop=PRDROP=IRDROP x ERDROP=0.5A x 2.2V = 1.1 W
RDrop=4.4 ohms / 2W (they don’t make 1.5W, or it is not a standard value)

FYI,

i made calcs again for 7,5 V battery and i obtained resistors of 5ohm for the 5V stepper coils and 1.25ohm for the 7,2 V stepper

The 1.25ohms resistors are needed or can i work the 7.2V motor with 7.5V without damage it?

My calculations were done for a voltage of 7.2V only as an example so you can recalculate for whatever voltage you will be using
but if the above comment is a reference to s a 2S LIPO battery then you need to recalculate because the voltage of a fully charged 2S LIPO battery is 8.4V (NOT 7.5V !)

Sorry now i dont know why u said "(7,2V - 5V)",
i said i have a power supply of 7,5 Volts, and two steppers, one of 5V and other one of 7,2V

R1 = (7,5 - 5) / 0,5 = 5 Ohm;
Pr1 = Vr1*Ir1 = 2,5V * 0,5 = 1,25WATT;

R2 = (7,5 - 7,2) / 0,24 = 1,25 Ohm;
Pr2 = Vr2*Ir2 = 0,3V * 0,24 = 0,072WATT; this was bad before :frowning:

i think with this calcs u undertand what i mean.
two steppers motors with 5V and 7.2V connected to a 7.5 external power supply, and R1, R2 are the resistor for not overload the steppers

the 7.5 are 5 batteries of 1.5.

Sorry again for my unknowledge, and please correct me if i said nonsense
Thanks

My calculations were done for a voltage of 7.2V only as an example so you can recalculate for whatever voltage you will be using

RECALCULATE FOR 7.5V
You could use the practice

i didnt saw that sorry