Do I need seperate ground planes for this circuit?

[Echelon 01]

I am using two seperate battery packs for servo motors and their controler. Dont asky why - this is a design constraint and cant be changed. Anyway the diagram is pretty self explainitory red is V+ and yellow is the clock pulse. I just wanted somone whos worked with servos before to tell me if this wiring would be correct. There are four grounds so I want to know which of them can be combined. Thanks

 

[bmcculla]

I've done a little work on servo motors and your diagram look correct for the most part. I don't know what the purpose of RL is though. As far as I know there is no reason for it. I'd check the input voltage spec for your servos; I beleive we provided a nice clean 5V supply for the servo we used.

To answer your question about why you need the second battery for the servo controller. Batteries have an internal impedance, if you draw a lot of current from them the voltage they supply drops. If the voltage drops below the input for your servo controller it will reset causing all sorts of problems.

Brent

 

[Echelon 01]

Thanks for the reply, The R load is a potentiometer I figured I should throw one in there incase I need to limit the current. I was assured by Hitech (the servo manufacturer) that these motors can take up to 6 volts - any more and they run hot, but I only need them on for a 3-4 minute competition, therefore the 6.4 volt supply is ok. My schematic has all the amp - hours rating for the batteries labeled as well as the maximum possible current drawn by each motor. So when they are all on at once (which will be only for a few seconds)it is almost 3 amps being drawn total. How can I determine how long the batteries will last? And also - the ground planes - no one told me if i should connect them all together or leave them how I have it. Thanks!

 

[Sebi]

As i read this sematic, all GND must be connected together, otherwise cannot work.But if You thinking about longer wires, the GND with one wire maybe disturbed the receiver, when the motors run with high current.The GND wire must be enough thick.