[NSRCA-discussion] regulators

[Ed Alt]

Yep, the i4C meter does put a small load on it to light the display and run. 
It's signal powered.

Ed

----- Original Message -----
From: "J.Oddino" <joddino at socal.rr.com>
To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
Sent: Wednesday, December 06, 2006 1:40 PM
Subject: Re: [NSRCA-discussion] regulators

> Bob, Ed, et al,
> First of all, the Jaccio (say Jackie O) regulator does not regulate at no
> load.  The i4C must put a slight load on it or you would see the full
> battery voltage at no load.  So the real drop you measured is about .18
> volts from the idle current condition.  This is made up of droop in the
> regulator and loss in the wiring.  The regulator drop is spec'd at .2 
> volts
> at 5 amps so it is proportionately less at 1.5 amps.  The regulator is a
> servo so it must have an error between commanded value and output to set 
> the
> "gain".  Gain is defined as output divided by commanded input.  We'd like 
> it
> to be one, but we'd end up with an oscillator or a regulator with a very
> slow response time.  I tried a design where I sensed the voltage on the
> receiver buss instead of internally in the regulator and had a terrible 
> time
> keeping it from oscillating.  The idea was to eliminate the drop between 
> the
> regulator and the receiver buss but I decided it wasn't worth it.
> There have been countless discussions about wiring losses and these are
> significant in IMAC and other giant scale type models.  I don't believe we
> need to worry about it in pattern planes but maybe we could provide 
> quicker
> elevator response in snaps for guys like Dave L would do everything they 
> can
> to get high speed and high torque.  Higher voltage at the servo is the
> easiest way to get that result.  Someday maybe I'll try to measure the
> voltage at the servo during flight.
> I totally agree with Ed that you are still better off with a Lithium pack
> and one regulator instead of a five cell NiMH pack and no regulator, 
> because
> even though you don't have perfect regulation at the servo, it is 
> consistent
> from flight to flight as the pack discharges.
>
> Jim O
>
>
> ----- 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 7:37 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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>> >
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