running a single HV servo on a regulated set up

[hanson]

As the title says really, does anyone know if it's possible to run a single HV servo in say a 5.5v regulated set up and is it as simple as just connecting the positive and negative direct from the lipo to the servo and then just the signal wire from the rx to the servo? Hope that makes sense.

Thanks,

Rich

[eckman]

it possible but what you try to do?

[Dedcalm]

If the ground reference is the same then this will work... for example there is a 700 at our club that runs the AR7100 Rx (internal reg) with all servo's running at the raw Li-Po voltage. Slightly more complicated wiring (which I have not seen in detail).

[hanson]

Hi eck, just toying with running a HV servo on pitchon the raptor, I think it would work, was just looking for confirmation.

Rich

[Tom Burgess]

Its actually a lot simpler to run 2S voltage to cyclics with the AR7100 Rob.

Question is though, why would you want to do this with just one servo?

Yes it is possible but I'm struggling to see an application for it ??

[Tom Burgess]

Sorry Hanson. My phone is only showing some replies and I didn't see ur post about running one on a Raptor pitch until after I had posted

[hanson]

No problem, yeah the rest of the electronics aren't designed for that kind of voltage, was just wanting to try a new servo. I'm on 35meg running an arizona, so the AR7100 is also not an option at the minute.

[Dedcalm]

You can still do it, assuming the ground on both side of the reg is common which i suspect is the case you could just connect the +ve wire from the unregulated li-po side to the servo you want to run the higher voltage. The signal is referenced to ground so would be unchanged as far as the servo electronics are concerned.

[hanson]

Hi Dedcalm, thanks for the reply. I'm not too sure what you mean by the ground being common on both sides of the reg? Are you saying it would be best to connect just the postive direct from the lipo and then the negative and signal wire from the rx?
Currently the lipo plugs into the arizona, which supplies the rx and everything bar the gyro and tail with 5.5v, then 5v to the tail I think? I have another connection on the lipo as the arizona connects to the lipo via deans and then there is a standard servo connector on the lipo as well.

Thanks,

Rich

[waveydavey]

He means that the -ve side of the supply to the regulator is the same as the output -ve from the regulator. Therefore you only need to run the +6v separate to get what your after. The problem is Rich if it's a 2S the voltage is going to be nearer 7.4v which is a bit more than your after if I'm reading the original post correctly.

[Andy from Sandy]

I'm not too sure what you mean by the ground being common on both sides of the reg?

Pull the positive lead from the servo plug and find a way to connect that to the positive of the Li-po. Then you need to confirm the negative lead of the li-po is common to the negative output on the RX. You can do this with the battery disconnected. Get an ohm meter or continuity tester and go from the deans plug to the rx.

EDIT: when you say HV I am assuming you are talking about something like a 8717 that can run on 8 volts?

[hanson]

Hi Dave, I'm after max volts to the one servo, so yeah 8 - 7.4v is fine to that one servo.

Hi Andy, Could I not connect both + and - direct from the lipo to the servo and just the signal wire coming from receiver to the servo? Or would the - have to come from the rx? It is a HV servo, wasnt the 8717 but yeah is rated for 8volts

Thanks,

Rich

[waveydavey]

Yes you can as long as the -ve going in is at the same potential as the -ve going out. IE put a multimeter across it direct from input to out and see what sort of reading you get. It should be short circuit. The -ve doesn't have to come from the receiver as they use a common power bus inside. In short you could run both -ve and +ve straight to the servo and the signal from the rx. Or save a bit of wire and some solder and just run the +ve