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I am building an hexapod 2DOF robot, and I had planned a Power supply (5V/5A) for all devices, like this :

enter image description here

Would that work and be safe?

I have another plan , to seperate the power between servos and others .

  • 5 x 1.2 AA battery = 6 V for Servos
  • 6 x 1.2 AA battery = 7.2 V for others

But, the battery pack for servos actually goes over voltage the ,it can be over 6 V whereas the maximum voltage for servo is 6 V.

is there a better option?

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1 Answer 1

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Several comments to help you on your way.

1) For your design of the regulator setup using the five 7805's do not wire all the regulator outputs together. Regulators wired in parallel generally is not a good idea er they will likely share the load evenly. Instead drive a small number of the servo connectors from each individual regulator.

2) For the 7805 regulators to work correctly you will need to to provide a minimum of at least 7 volts. Slightly more would be better.

3) The 1N4001 input diode that you show for driving the five regulators is not up too the job is passing 5A. That part is designed to pass a maximum of 1A. So use one diode per regulator.

4) When you separate the regulator outputs make sure to provide some capacitance on each regulator output.

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  • \$\begingroup\$ I had fixed my design , sphotos-h.ak.fbcdn.net/hphotos-ak-snc6/s320x320/… 1) I wire all ouputs together is for share all load to all 7805 2) Yes , I use 6 x 1.2v AA = 7.2 volt 3) yeah, you are right 4) Would you tell me why I have to provide some capacitance on each regulator ? But my main question , still be answered yet, It is OK , if I use more than 6 volt for servos ( but it should the 6 volt due to 5x 1.2v AA baterries is 6 volt , but when I charge that batteries , it is goes over 6 volt ) \$\endgroup\$
    – Edward Hiskia
    Feb 18, 2013 at 15:33
  • \$\begingroup\$ And I need some advice from you : I have to provide power for 12 servos (I used servo standart parallax) , from datasheet , each servos current consumption is 50mA (max) , so for all servos is 0.6 A , right ? so my power supply due enough for all circuit . but why my regulator goes overheating whereas the load not over 50% from its power \$\endgroup\$
    – Edward Hiskia
    Feb 18, 2013 at 15:41
  • \$\begingroup\$ @EdwardHiskia - Good rework of the schematic design. Each regulator can now supply up to 1A for each servo. Capacitors are needed for each regulator output because the manufacturer specifies that for the part in the data sheet. As far as your input voltage....7.2V input for the 7805 parts is barely enough IF the battery pack was attached DIRECTLY to the input of the regulator. Since you have a polarity protection diode there in front of each regulator you will need to provide almost 1 more volt of input voltage in order for the regulators to work properly. You should plan for a mimimum of 8V. \$\endgroup\$
    – Michael Karas
    Feb 18, 2013 at 23:50
  • \$\begingroup\$ @EdwardHiskia -- OOPS - I checked your new schematic again. Remove the wire that shorts all the regulator outputs together. You DO NOT want to short the five 7805 outputs together. I said this in my initial answer. \$\endgroup\$
    – Michael Karas
    Feb 18, 2013 at 23:53

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