"Miracle switch" failures

[wgalligan]

Heck...I cant even find a can of decent tuner cleaner anymore.

> Hey Dean,
> There are a lot of things in our radios that could be better.  The problem
> is that they work awfully good so it would be difficult to sell a better one
> unless the price were lower or it had some feature the present ones don't
> have.  I keep thinking of some sort of stepping motor technology.  Someday.
> Jim
> ----- Original Message -----
> From: "Dean Pappas" <d.pappas at kodeos.com>
> To: <discussion at nsrca.org>
> Sent: Tuesday, March 25, 2003 10:26 AM
> Subject: RE: "Miracle switch" failures
> 
> 
> Cans of tuner contact cleaner have gone the way of buggy whips: wait a
> minute, the Amish still use the buggy whips, but no TVs. Now we need to get
> rid of the pot wiper contacts in the servos. Gosh Jim, I remember talking to
> you about that over a cup of coffee in Toledo back in '83 or so. It still
> hasn't happened.
> Dean
> 
> -----Original Message-----
> From: JOddino [mailto:JOddino at socal.rr.com]
> Sent: Tuesday, March 25, 2003 1:19 PM
> To: discussion at nsrca.org
> Subject: Re: "Miracle switch" failures
> 
> 
> John,
> I might need to apologize.  I keep thinking everyone remembers mechanical
> tuners.  Perhaps you are too young.
> Jim
> ----- Original Message -----
> From: "JOddino" <JOddino at socal.rr.com>
> To: <discussion at nsrca.org>
> Sent: Tuesday, March 25, 2003 9:04 AM
> Subject: Re: "Miracle switch" failures
> 
> 
> > 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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