does anyone know if the hobbyking 50-60A ESC can be used with a reciever that user a seperate power supply to the power systems supply. The ESC has no ubec

If the ESC has no BEC then you will need a separate UBEC or receiver battery to supply the receiver/servos. But that doesn't stop you using the ESC to control the motor.

Steve

i know, what i mean is can i have a seperate power supply from a different battery powering my servos and a main battery that my ESC uses for the powerplant? just wondering if they would interfere

If you have an ESC with BEC and want to use a spearate BEC or even a 4.8v battery pack, then the ESC's BEC should be disabled. The easy way to do that is remove the red +ive connector from the ESC to Rx connector.

Pictures on how to here - http://www.rcgroups.com/forums/showp...89&postcount=7

Originally Posted by rangamatchstic

i know, what i mean is can i have a seperate power supply from a different battery powering my servos and a main battery that my ESC uses for the powerplant? just wondering if they would interfere

Yes, you can; I have a couple aircraft powered this way. In fact, I have one aircraft with a battery powering two BECs, one for the receiver and servos, the other for the retracts. A larger battery powers the motor ESC.

ok thanks, i think i was getting worried by what happens if you put two circuits together with one that is providing analogue information to the other but being powered off different power supplies, you get floating voltage. but RC stuff uses PPM (PWM) so it doesnt have thsi problem.

Also, the negative of the power sources are all connected together, so there is no real floating.

Originally Posted by Wintr

Also, the negative of the power sources are all connected together, so there is no real floating.

i cant have the negative terminals connected as im running the two systems off completley difffrent power suplies. One supply is 4 AA batts to give me 6v for the reciever and autonomous system and the other is a 4s lipo to power the ESC and motor.

This shows a typical wiring scheme for using an external BEC:

http://www.castlecreations.com/produ...ec_wiring.html

More info on that particular BEC here:

http://www.castlecreations.com/products/ccbec.html#

Jack

....you still dont get what i mean -.-
fine ill draw up a diagram later

Originally Posted by rangamatchstic

i cant have the negative terminals connected as im running the two systems off completley difffrent power suplies. One supply is 4 AA batts to give me 6v for the reciever and autonomous system and the other is a 4s lipo to power the ESC and motor.

And what exactly do you think stops you from connecting the two negatives together ?

In fact if you've got the (4S lipo powered) ESC plugged into the (4AA powered) receiver then the negatives ARE already connected....that's what the black wire in the ESC connector does .

Steve

how would you connect the two power supplies then? if you did that you would be basicly putting the two supplies in parrlel which wouldnt work, i may be wrong as im stupidly tired when im typing this but ill just stick with two seperate sets of wiring for each supply as the supplies are coming from different places in the plane anyway.

The supplies are only connected at the negative side. The positive side of the flight motor battery only supplies the ESC, and the positive side of the other source only supplies the receiver and servos. There is no path between the two power sources, other than the ground/negative reference that passes through the receiver. To make sure, the center wire of the cable from the ESC to the receiver must be taken out of the connector and turned back. If you substitute a battery for the BEC in the first Castle diagram, meaning there is no connection of the receiver battery and the motor battery, the common point is the ground through the receiver.

ok thanks, even if i dont connect the two negatives because the batts are in different sections of the plane do i still have to take out the negative wire between the ESC and receiver?

Do not take out the negative wire - the ESC has to read the pulse coming from the receiver, and, without the reference ground, noise from the power pulses to the motor can interfere. Just take out the positive wire, unless the ESC has an opto input, and needs it to function.