How to pick a power supply

Question

I am trying to make a circuit that uses three stepper motors each rated at .5amps at 5 volts. If I use a PC power supply (which can supply 30 amps at 5 volts) would the motors burn out due to too many amps or would they just use what they need.

Answer 1

plz Try this 1.5 to 30V with 5 amp power suply diagram.

http://www.aaroncake.net/Circuits/supply...

Answer 2

30 amps is the maximum output of the power supply, the components will use only what they need.  

Answer 3

Generally they will draw only the current required & if they are rated at 5 volts, then will be happy with 5 volts across them.

But, I guess you must have a switching circuit making the steps.  Some sort of power device must be sequencing the steps or the things are not going to turn.  All such devices will drop some potential (volts).  If they drop too much you won't get enough voltage across the motor windings to turn any significant load.

Likely you are fine.  Likely all will work fine.  with a 5 volt supply, you might not want to use power devices that are too in efficient: drop too much across themselves.  For example, if the supply is 5 volts & the power device drops 1 volt when "on" the motor only sees 4 volts.  Likely this is fine.  Again, the current will mostly look after itself.  If the motor windings are rated at .5 A your power devices should be rated at at least 0.5 A also. (& at least 5 volts).

PS: Motors produce back EMF that reduces the effective voltage.  The back EMF also can appear when things switch.  Check whether your drive circuit has some protection for the power device from back EMF, eg a backwards diode across the motor.  If you're using a drive IC it may be included.  But, might be worth checking.