Power drain? two servos and esc.

[limpet]

Looking on the net at wiring for the regulator there are various caps used, is it important to get the correct ratings or can I just match them if they are within certain specs?

[peterwaller]

All these discussions reminded me that some time ago I was thinking of making some BECs but finally dropped the idea.
Looking through my old PCBs I found I had got as far as etching and drilling a board.
I have just fitted the components and it all seems to work wired as per the diagram.
All you would need to do is plug the flying lead with the servo connector into the receiver channel you are using for the servos and plug the servo into the three pin plug on the back of the board. then just connect the black and red power leads to your battery.
Not knowing the servo's you are using I can't be certain it will provide enough power but it gives 1.5A.


I am unlikely to ever use it so if you PM me your address I will post it to you.

[Rapidrory]

The exact values aren't important as long as they're as high as the minimum specified on the datasheet. It's always best to try and use the highest value output cap you can (within reason) so that the voltage is stable even with high current spikes. 100uF is usually a good bet.
The input cap is less important, as a lipo battery will keep up with most of the current demand drawn by a servo. It's good practice to put one on though as it keeps noise out of the rest of the system. I'd recommend at least 10uF.

[limpet]

Thanks again for the help, its coming thick and fast now
The servos are Turnigy TGY90S. I`ve reversed one and mounted them base to base, they look quite neat too. When I originally tried reversing one I neglected to do the pot as well and then I didn`t get time for a while.

[Rapidrory]

If you want to get the full power out of your servos, you could always use an adjustable regulator to supply the maximum 6v to the servos... the only tricky bit about that is picking the right resistors to adjust the regulator, but there are online calculators which'll work them out for you. Most regulator IC have an adjustable version, so as long as you make sure it has less than a 1.4V dropout voltage (to run 6v from a 7.4V lipo), It's easy enough to get the full power.

I've done it before and have run a 5kg/cm servo in stall off a similar sized adjustable reg, and it's been fine. Just check the voltage first, as if you get the resistors the wrong way round you only get 3v, out which is no good to anyone

EDIT: Interesting choice of servos, what was the reason for using those particular ones? Power/weight/speed ratios all seem a little low for a weapons servo..

[peterwaller]

Did the regulator board fix the problem.

[limpet]

Hi All,
Pete: Thanks for the board Pete its working well! I managed to fit it whilst at Burgess Hill and it got a good testing by John during most of the day. (tried to pm you on the day but guess it didn`t work)
Rory: The Turnigy servos are metal geared and a good price so I got them to see what they were like. I got four for about £12 I think.
More power to the servos is something I`d like to have a go at, something for the next version probably.