"Miracle switch" failures
s.vannostrand at kodak.com
s.vannostrand at kodak.com
Thu Mar 27 07:55:28 AKST 2003
You are right. The regulator is bad. Jim Oddino thinks this is unlikely
to happen in the air. My experience concurs. It could fail during use,
but is more likely to fail on powerup. Therefore it is likely that the
failure occurred on the ground, but was not evident until the charge flash
burned off. No way you could have checked for this, is there?
I have a Voltwatch on my Entropy and have used it on all non-canopy
planes. This would tell you about a voltage low. Maybe we need to start
using them on the Aries too>
--Lance
wgalligan
<wgalligan at cnbco To: Lance VanNostrand/249603/US/EKC at Kodak
m.net> cc:
Subject: Re: "Miracle switch" failures
03/27/03 10:47
AM
yes... with no load it is at 5.97v normal but with just my ESV on it it
only shows 4.2v.
certainly the load of an ESV shouldnt trick the regulator to drop the
voltage that low.
> So, you are saying that the voltage after the regulator (at the receiver)
> was fine with no load,but dropped to 4.4v wiht a load. What load did you
> apply?
>
> ----- Forwarded by Lance VanNostrand/249603/US/EKC on 03/27/03 10:06 AM
> -----
>
> wgalligan
> <wgalligan at cnbcom To:
"discussion at nsrca.org" <discussion at nsrca.org>
> .net> cc:
> Sent by: Subject: Re: "Miracle
switch" failures
> discussion-reques
> t at nsrca.org
>
>
> 03/25/03 12:30 PM
> Please respond to
> discussion
>
>
>
>
>
>
> I tested battery hooked to the switch and off the switch. Check voltage
on
> the input side of battery with VOM while expanded meter was hooked to
> output side. IN all cases the battery was at 6.5+v. the output when
> checked with just the VOM was 5.97v(normal) but when I hooked up a loaded
> meter the voltage dropped to 4.2v when th e inout was at 6.5.
> When the battery had a fresh charge the output was like 4.4v just enough
to
> get it in the air and after a littel discharge it had to be dropping
below
> the recievers voltage threshold.
>
> Anyway.... off to finish building the new one.
>
> Wayne
>
> > First of all the electronic "switch" is a device used in a linear mode
> when
> > regulating. If the input voltage drops below the set regulated voltage
> it
> > will saturate and if it is a good regulator will have an on resitance
of
> 50
> > milliohms or so. I didn't hear if he checked the input voltage under
the
> > same conditions he measured 4.2 volts on the output. Either the input
> > voltage was low or the on resistance was high and/or the load current
was
> > too high.
> > Second, the electronic switch/regulator is not in parallel or tandem
with
> > the mechanical switch. If the mechanical switch fell off the plane you
> > would not lose power. In fact I don't even have a mechanical switch on
> my
> > new plane. I use a safeing plug to turn it off.
> > The device I use protects itself and I wouldn't know how to make it
fail
> > within its rated operating conditions. You can put a dead short on the
> > output and not hurt anything. Try that with your mechanical switch but
> have
> > a fire extinguisher handy.
> > Think about how long the old mechanical tuners on TVs lasted. When was
> the
> > last time you heard of an electronic tuner going bad? I rest my case.
> > Jim
> > ----- Original Message -----
> > From: "John Ferrell" <johnferrell at earthlink.net>
> > To: <discussion at nsrca.org>
> > Sent: Tuesday, March 25, 2003 6:24 AM
> > Subject: Re: "Miracle switch" failures
> >
> >
> > > If I understand the failure conditions, the electronic switch was
> > paralleled
> > > with a mechanical switch.
> > > That is not something that would be considered a 'normal'
configuration
> > for
> > > the electronic switch.
> > > I refrain from using these devices because I have never had a switch
> > problem
> > > with a Futaba switch.
> > > Most electronic power switching devices that I am aware of are MOSFET
> > > technology.
> > > These devices switch many amps with great reliability, but are
> extremely
> > > vulnerable to voltage spikes.
> > > The inputs and outputs are protected by internal diodes from these
> spikes.
> > > I have been unable to puzzle out if there is an unprotected
> input-output
> > > junction.
> > > Here is a possible scenario:
> > > The mechanical switch is turned off generating a spike that
damages
> > the
> > > elecronic switch in a failure
> > > mode that drags down the receiver voltage feed.
> > > My personal conclusion is that either switch will work as advertised,
> but
> > > when used in tandem it is
> > > not a matter of if it will fail but when it will fail.
> > >
> > > John Ferrell
> > > 6241 Phillippi Rd
> > > Julian NC 27283
> > > Phone: (336)685-9606
> > > Dixie Competition Products
> > > NSRCA 479 AMA 4190 W8CCW
> > > "My Competition is Not My Enemy"
> > >
> > >
> > >
> > > ----- Original Message -----
> > > From: <s.vannostrand at kodak.com>
> > > To: <discussion at nsrca.org>
> > > Sent: Monday, March 24, 2003 1:16 PM
> > > Subject: "Miracle switch" failures
> > >
> > >
> > > > I know there are some vendors and users of those voltage regulators
> with
> > > > the built in switch. One mfg calls it the miracle switch. I have
> one,
> > > > hooked it up, am using it with no problems so far, but I may be
just
> > > lucky.
> > > > Is there a right/wrong way to hook up the connectors? I have a
radio
> > > south
> > > > one and there are two male connectors (one for the receiver, and
one
> for
> > > > recharging), and one female (for the battery input). The system
> works
> > > with
> > > > either male plugged into the receiver. Based on Wayne's sad story
> below
> > > > I'm wondering if maybe only one should be connected to the receiver
> in
> > > > order to maintain voltage when the switch fails.
> > > >
> > > > Anyone know if there is a sure way to tell if you have it hooked up
> > > > correctly?
> > > >
> > > >
> > > > Wayne writes, " I am/was using a MCI Miracle switch that is a
> regulator
> > > and
> > > > has fail safe if the mechanical switch contacts fail the switch
stays
> on
> > > > all the time. I tested the battery and it checked at 6.5v. I
> checked
> > > > through the charge port and 6.5v. But when I checked it through
the
> > > > connector to the receiver it only registered 4.25v just below the
> > > > receivers voltage threshold. "
> > > >
> > > > --Lance
> > > >
> > > >
> > > >
> > > >
> > > > =====================================
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