[NSRCA-discussion] regulators

[Robert Mairs]

Thanks Ed, Jim O.  I have a lot better understanding of how these work now.
Bob


----- Original Message ----- 
From: "Ed Alt" <ed_alt at hotmail.com>
To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
Sent: Wednesday, December 06, 2006 10:37 AM
Subject: Re: [NSRCA-discussion] regulators


> Bob:
> The regulator is probably doing just fine. Every regulator that's out 
> there
> for use in our models has one thing in common.  They regulate the voltage
> output at the point that the regulator is physically connected to.  They
> can't "see" the actual voltage at the end of the wires where your servos
> are. They can only see it at the point where the pins leave the regulator 
> IC
> package.  What is happening is that a voltage drop is developing across 
> all
> of the wiring in between the regulator and the load where you are 
> measuring.
> The voltage drop is calculated by E=IR, where voltage is E, current is I 
> and
> R is resistance.
>
> There are two ways to accomplish regulation at the load.  One is to have a
> remote sense design to the voltage regulator system, which actually takes
> the true voltage at the point where the load connects and feeds that back 
> to
> the regulator, to permit the regulator to compensate for the losses in the
> wiring. In practice, this would not work for our application, since the 
> load
> varies at each servo, so if servo 1 is drawing a bunch of current and thus
> experiencing a lower voltage, the other servos actually don't see a 
> voltage
> as low as the one drawing the load. So if you boosted the regulator 
> voltage
> to make servo #1 happy, the others would see a higher voltage.  The end
> result is that the voltage would be all over the place on the high side,
> which is not desireable.
>
> The other thing you could do is just place a regulator at each servo.  Jim
> Oddino could tell you more about it, since he has this setup flying, but
> it's a perfectly good method if you don't mind doing the wiring up at the
> end of each extension. It has several benefits, some minor drawbacks,
> overall it's a cool idea.  Believe it or not, even though you are seeing
> this effect of wiring resistance, you are still better off with the one
> regulator that you have.  It is taking away the effect of the battery's
> internal resistance and all of the wiring in between it and the battery, 
> so
> the servos are in fact getting a more constant supply than they otherwise
> would.
>
> Ed
>
> ----- Original Message -----
> From: "Robert Mairs" <robertm at sssnet.com>
> To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
> Sent: Wednesday, December 06, 2006 7:53 AM
> Subject: [NSRCA-discussion] regulators
>
>> I've got a Jaico that regulates to 6.11 volts.   Using a 480 mah TP lipo,
>> and the Jaico, I got the following.
>>
>> no load, 6.11v
>> 500mah load, 5.72v
>> 1A load, 5.63v
>> 1.5A load, 5.54v
>>
>> Just with the battery, no regulator I get
>>
>> no load, 8.2v
>> 500mah, 7.84v
>> 1A, 7.51v
>> 1.5A, 7.2v
>>
>> I don't understand.  Why doesn't the regulated voltage stay at 6.11v with
>> a
>> load?  I always thought using a regulator was supposed to give you a
>> constant voltage so the servos reaction would always be the same, yet it
>> acts just like a battery,  just not as great a drop off it seems.
>>
>>
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