Powering a 5V and a 9V circuit from one 9V battery -- isolation help?

** Hotmail & GG !

Double whammy .....

** What sort of servos draw under 150mA ?

The servo load current is hammering the battery and causing the noise.

Using the 5 volt reg has no effect on this.

** Yeah - use as decent 9 volt battery and a decent reg IC. ** Yep, 4 or 5 AAA cells, Ni-Cd or NiMH

The very low internal resistance will make a BIG improvement.

...... Phil

It's tried-and-true solution to have separate power supplies for the motors and the control circuitry. Your system has already demonstrated that it works well this way, so if you go with the flow, you can optimize the batteries for each subsystem. Your control circuit and video might be able to get by with a couple of lightweight lithium cells @ 3 volts each. Meanwhile, your servo motors could run on some sort of rechargeable cells because that's where the bulk of your power is being consumed. This also allows you to maintain full control and video even when the servo motor batteries are getting low.

-- Joe Legris

I've done this before without any problems. The camera was 12 volts and the servos were powered from a 7805 regulator with about 100uf on both the input and output. You dont need a fancy low-dropout regulator for this application.

Also, watch out for any common ground connections, run both bach to the battery seperately. Or, try physically moving the servos away from the camera to see if the coupling is inductive from the motor coils.

Good luck, Luhan

Thanks all for the rapid and helpful responses! On a Sunday morning, no less.

Hmmm. Is there something I can add to become a triple threat?

Sure,

1. Top-post,
2. Add a big ascii-graphics sig,
3. Don't quote the posts you reply to,
4. Use 733t spelling (l33t speak),
5. Tell the old guard they're newbies, etc, etc.

-jiw

Yeah - keep feeding the troll. ;-)

Good Luck! Rich