So I picked up this nifty Davtron digital electric clock/timer at Sun N Fun.
It's exactly the same model I had in my Warrior (Model 800), and I found a
good price for it. (Roughly 4 times what it's really worth -- a bargain in
aviation!) Our wind-up clock had become sporadic in cold weather, and I
kept forgetting to wind it anyway...

My A&P took one look at the box and said "This will be a snap to install!"
This should have set off warning alarms right away, but it didn't. We
decided to do it at the annual, when everything was already ripped apart
anyway.

So, after most of the annual was complete, Darryl (the junior A&P in our
2-man shop) dug into it. As expected, it turned out to be a real
son-of-a-bitch getting at the backside of the panel. I ended up standing on
my head under the panel, holding the clock in place with the very tips of my
fingers, while Darryl carefully dropped the tiny little retaining screws
onto my belly, over and over again. It was fun! Really!

Eventually, through sheer persistence, he got the damned screws threaded in.
Then the real fun began -- wiring! The directions clearly called for the
dimmer control wire to be connected to one of the panel lights, and the hot
lead to go directly to the battery. Unfortunately the battery was in the
way back of the plane -- not exactly handy -- so Darryl decided to wire it
into the hot side of the master switch.

This made sense to me -- which, again, should have set off warning bells in
my head, but didn't -- as the master switch was a heckuva lot closer than
the battery.

So I picked the plane up today, after reassembling the last little bits and
pieces. Everything looked great, the engine fired up easily, I taxied about
40 yards -- and the clock blinked out and died....

Immediately spinning the plane around, I shut the engine and master down --
and the clock came back to life! So, I turned the master switch back on,
and *poof* -- 15 seconds later, the clock went blank.

What the hell!?

Darryl was completely stumped, and a huddle of wise old airport bums
immediately assembled. It was obvious that hooking up to the "hot" side of
the master switch was NOT giving us continuous power -- but why?

No one knew, and I had to get back to the hotel. I took the plane back to
my hangar, and left the wise men standing there scratching their heads.

As soon as I got back to the inn, I called Davtron. Describing the symptoms
to them, they immediately knew the problem. Apparently the Piper master
switch -- on the hot side only -- "powers down" after 15 seconds! Some
solenoid somewhere gets thrown, grounding the circuit and killing power to
the hot side of the master switch.

They said I had two choices: 1) Run the power directly to the battery,
clear in the back of the plane, or 2) send the clock into Davtron, for free
installation of a battery back up. This battery allows the clock to be
connected to the avionics master, rather than a "hot" wire.

I immediately called Darryl, and gave him the options. He has agreed to
fix the problem on Monday, whatever it takes, free of charge. Rather than
take the thing out, send it to California, and reinstall it -- he's opted to
run the wire to the battery...

Live and learn -- who'd ever think that installing a gol-danged CLOCK would
be so hard?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay... I have a cheaper alternative.. I carry my "ships clock" on my wrist..

LOL
BT

"Jay Honeck" > wrote in message
news:lEurc.36031$gr.3583857@attbi_s52...
> So I picked up this nifty Davtron digital electric clock/timer at Sun N
Fun.
> It's exactly the same model I had in my Warrior (Model 800), and I found a
> good price for it. (Roughly 4 times what it's really worth -- a bargain
in
> aviation!) Our wind-up clock had become sporadic in cold weather, and I
> kept forgetting to wind it anyway...
>
> My A&P took one look at the box and said "This will be a snap to install!"
> This should have set off warning alarms right away, but it didn't. We
> decided to do it at the annual, when everything was already ripped apart
> anyway.
>
> So, after most of the annual was complete, Darryl (the junior A&P in our
> 2-man shop) dug into it. As expected, it turned out to be a real
> son-of-a-bitch getting at the backside of the panel. I ended up standing
on
> my head under the panel, holding the clock in place with the very tips of
my
> fingers, while Darryl carefully dropped the tiny little retaining screws
> onto my belly, over and over again. It was fun! Really!
>
> Eventually, through sheer persistence, he got the damned screws threaded
in.
> Then the real fun began -- wiring! The directions clearly called for the
> dimmer control wire to be connected to one of the panel lights, and the
hot
> lead to go directly to the battery. Unfortunately the battery was in the
> way back of the plane -- not exactly handy -- so Darryl decided to wire it
> into the hot side of the master switch.
>
> This made sense to me -- which, again, should have set off warning bells
in
> my head, but didn't -- as the master switch was a heckuva lot closer than
> the battery.
>
> So I picked the plane up today, after reassembling the last little bits
and
> pieces. Everything looked great, the engine fired up easily, I taxied
about
> 40 yards -- and the clock blinked out and died....
>
> Immediately spinning the plane around, I shut the engine and master
down --
> and the clock came back to life! So, I turned the master switch back on,
> and *poof* -- 15 seconds later, the clock went blank.
>
> What the hell!?
>
> Darryl was completely stumped, and a huddle of wise old airport bums
> immediately assembled. It was obvious that hooking up to the "hot" side
of
> the master switch was NOT giving us continuous power -- but why?
>
> No one knew, and I had to get back to the hotel. I took the plane back to
> my hangar, and left the wise men standing there scratching their heads.
>
> As soon as I got back to the inn, I called Davtron. Describing the
symptoms
> to them, they immediately knew the problem. Apparently the Piper master
> switch -- on the hot side only -- "powers down" after 15 seconds! Some
> solenoid somewhere gets thrown, grounding the circuit and killing power to
> the hot side of the master switch.
>
> They said I had two choices: 1) Run the power directly to the battery,
> clear in the back of the plane, or 2) send the clock into Davtron, for
free
> installation of a battery back up. This battery allows the clock to be
> connected to the avionics master, rather than a "hot" wire.
>
> I immediately called Darryl, and gave him the options. He has agreed to
> fix the problem on Monday, whatever it takes, free of charge. Rather
than
> take the thing out, send it to California, and reinstall it -- he's opted
to
> run the wire to the battery...
>
> Live and learn -- who'd ever think that installing a gol-danged CLOCK
would
> be so hard?
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

> Jay... I have a cheaper alternative.. I carry my "ships clock" on my
wrist..

Funny, that's what one of the wise old heads on the field said, while Darryl
was poking around: "Why in HELL do you need an electric CLOCK, for
Chrissakes? Doncha got a WATCH?"

:-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay wrote, "Apparently the Piper master switch -- on the hot side only --
"powers down" after 15 seconds! Some solenoid somewhere gets thrown,
grounding the circuit and killing power to the hot side of the master
switch."

What?! I'd love to see a diagram of that circuit.

Jon

Jon Woellhaf wrote:
>
> Jay wrote, "Apparently the Piper master switch -- on the hot side only --
> "powers down" after 15 seconds! Some solenoid somewhere gets thrown,
> grounding the circuit and killing power to the hot side of the master
> switch."
>
> What?! I'd love to see a diagram of that circuit.

Me to.
That sounds like a bizzare system !

Probably has something to do with it being a low wing....

--
Jim Carter
"MC" > wrote in message
...
> Jon Woellhaf wrote:
> >
> > Jay wrote, "Apparently the Piper master switch -- on the hot side
only --
> > "powers down" after 15 seconds! Some solenoid somewhere gets thrown,
> > grounding the circuit and killing power to the hot side of the master
> > switch."
> >
> > What?! I'd love to see a diagram of that circuit.
>
> Me to.
> That sounds like a bizzare system !

Jon Woellhaf > wrote:
:> Jay wrote, "Apparently the Piper master switch -- on the hot side only --
:> "powers down" after 15 seconds! Some solenoid somewhere gets thrown,
:> grounding the circuit and killing power to the hot side of the master
:> switch."

: What?! I'd love to see a diagram of that circuit.

The Piper master switch does no such thing. The piper master switch supplies
GROUND to the master solenoid. Whne the switch is off, no current is flowing
through the solenoid windings, and the master switch appears to have +12V
battery connected to it - which it does - through the solenoid windings.
When you flip the master on, it grounds the wire from the solenoid that
previously appeared to have +12V battery on it. (Just like the dome light
switch on every car except for Fords.)

ASCII schematic:

(+ Battery)---(solenoid)-----(master switch)-----(- battery)

--
Aaron Coolidge

"Jay Honeck" > wrote in message
news:wRurc.92436$iF6.8041834@attbi_s02...
> > Jay... I have a cheaper alternative.. I carry my "ships clock" on my
> wrist..
>
> Funny, that's what one of the wise old heads on the field said, while
Darryl
> was poking around: "Why in HELL do you need an electric CLOCK, for
> Chrissakes? Doncha got a WATCH?"
>

I'm with Jay on this one. I had an old analog clock in my 152, it wasn't
working, and I tried using my watch for things, but I much prefer to have
the clock right up there in my scan. I installed the 800 Davtron as well,
which is pretty basic (wanted the one that had temperature and voltage as
well, but didn't like the additional $300 for it and who knows how much the
install would have been since there would be additional wiring) Just has
local time, GMT, and a timer but now that I have it and have flown with it
for a bit, I don't ever want to go back to that old analog clock or the
watch on my wrist.

--
Louis L. Perley III
N46000


> :-)
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

> ASCII schematic:
>
> (+ Battery)---(solenoid)-----(master switch)-----(- battery)

Thanks, Aaron.

For us electrical dimwits, can you explain the purpose of this circuit?

Also, why is there a 7-second delay after turning the master switch on?

Here's how it works:

1. The clock is connected to the "hot" side of the master.
2. It works fine with master "off"
3. Turn Master Switch "on" -- works fine for seven seconds.
4. At seven seconds, the clock goes out.
5. Turn Master Switch "off" and the clock comes back on.

What's going on? Why is this circuit set up to do this?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

On Sat, 22 May 2004 04:38:34 GMT, "Jay Honeck"
> wrote:

>> ASCII schematic:
>>
>> (+ Battery)---(solenoid)-----(master switch)-----(- battery)
>
>Thanks, Aaron.
>
>For us electrical dimwits, can you explain the purpose of this circuit?
>
>Also, why is there a 7-second delay after turning the master switch on?
>
>Here's how it works:
>
>1. The clock is connected to the "hot" side of the master.
>2. It works fine with master "off"
>3. Turn Master Switch "on" -- works fine for seven seconds.
>4. At seven seconds, the clock goes out.
>5. Turn Master Switch "off" and the clock comes back on.
>
>What's going on? Why is this circuit set up to do this?


I think this is whats going on Jay,
First, Aaron is right..the master switch is just a ground path for the
master solenoid.
The master solenoid has 12 volts going to it but dosen't work untill
the master switch is ON ..providing a ground path for it.
So with the master OFF, one side of the switch is at 12 volts (the 12
volts going thru the solenoid coil, and the other side is at ground.
Your clock must be hooked up to the hot side of the master switch, and
gets 12 volts thru the solenoid coil.
When you throw the master ON, BOTH sides of the master switch are now
at ground..and the master is now supplying a ground path to the
solenoid coil. Your clock power feed is now at ground and it croaks.
Why the 7 sec. delay?.... I bet you will find if you provide 12v to
the clock thru any source, then kill it..it will last for 7
sec..probably some capacitance built into the clock power circuits.

Aaron Coolidge > wrote:

> The Piper master switch does no such thing. The piper master switch supplies
> GROUND to the master solenoid.

Indeed. Arn't all aircraft this way? My Bonanza certainly is.


--
Frank Stutzman
Bonanza N494B "Hula Girl"
Hood River, OR

Jay Honeck wrote:

> Also, why is there a 7-second delay after turning the master switch on?
>
The 7-second delay is probably in your clock. That's how long the clock
continues to run after it's power is removed.


> Here's how it works:
>
> 1. The clock is connected to the "hot" side of the master.
>
The "hot" side of the master does not go to the battery; rather, it goes to the
COIL(-) of the master contactor. The battery goes to the *other* side [coil(+)]

Your clock is thus not connected directly to the battery. The COIL of the
contactor is between the battery and the clock.


> 2. It works fine with master "off"
>
Yes, because it's receiving voltage *thru* the COIL (a resistance of several
tens of ohms or so.) It works just fine.


> 3. Turn Master Switch "on" -- works fine for seven seconds.
>
The master switch connects the coil(-) to GROUND. The voltage at the "hot" side
of the master (and the clock) goes to ZERO. Current flows from the battery thru
the coil and switch to ground; causing the master contactor to close (you'll
hear the "clunk" if you listen) and the airplane's electrical system is energized.


> 4. At seven seconds, the clock goes out.
>
Because that's how long the clock runs after power is removed.


> 5. Turn Master Switch "off" and the clock comes back on.
>
Yes, the COIL is un-grounded, the contactor opens ("clunk") and the electrical
system is de-energized. The voltage at the "hot" side of the master returns,
and the clock runs again (unless it's wiped out by the inductive kick-back from
the coil :)


> What's going on? Why is this circuit set up to do this?
>
Ask the idiot (Certified Mechanic?) who wired in your clock that way!

Frank Stutzman > wrote in
:

> Aaron Coolidge > wrote:
>
>> The Piper master switch does no such thing. The piper master switch
>> supplies GROUND to the master solenoid.
>
> Indeed. Arn't all aircraft this way? My Bonanza certainly is.
>

I'm no A&P but if that's the case, then Jay's A&P should be able to wire
the hot side of the clock to the hot side of the coil input of the Master
Solenoid, and the ground of the clock to the ground side of the master
switch, and the clock will stay on all the time...


Is the Master solenoid closer to the front of the panel than the Battery?

So why dis Piper wire it that way? Cessna has a separate circuit, the keep
alive circuit for what ever piece of equipment that needs it, that is wired
to the hot side of the master contactor. There is a fuse right next to the
master contactor for this circuit.



"Mark Mallory" > wrote in message
...
>
> Jay Honeck wrote:
>
> > Also, why is there a 7-second delay after turning the master switch on?
> >
> The 7-second delay is probably in your clock. That's how long the clock
> continues to run after it's power is removed.
>
>
> > Here's how it works:
> >
> > 1. The clock is connected to the "hot" side of the master.
> >
> The "hot" side of the master does not go to the battery; rather, it goes
to the
> COIL(-) of the master contactor. The battery goes to the *other* side
[coil(+)]
>
> Your clock is thus not connected directly to the battery. The COIL of the
> contactor is between the battery and the clock.
>
>
> > 2. It works fine with master "off"
> >
> Yes, because it's receiving voltage *thru* the COIL (a resistance of
several
> tens of ohms or so.) It works just fine.
>
>
> > 3. Turn Master Switch "on" -- works fine for seven seconds.
> >
> The master switch connects the coil(-) to GROUND. The voltage at the
"hot" side
> of the master (and the clock) goes to ZERO. Current flows from the
battery thru
> the coil and switch to ground; causing the master contactor to close
(you'll
> hear the "clunk" if you listen) and the airplane's electrical system is
energized.
>
>
> > 4. At seven seconds, the clock goes out.
> >
> Because that's how long the clock runs after power is removed.
>
>
> > 5. Turn Master Switch "off" and the clock comes back on.
> >
> Yes, the COIL is un-grounded, the contactor opens ("clunk") and the
electrical
> system is de-energized. The voltage at the "hot" side of the master
returns,
> and the clock runs again (unless it's wiped out by the inductive kick-back
from
> the coil :)
>
>
> > What's going on? Why is this circuit set up to do this?
> >
> Ask the idiot (Certified Mechanic?) who wired in your clock that way!
>
>

"Jay Honeck" > wrote in message news:<ePArc.38163$gr.3760706@attbi_s52>...
> > ASCII schematic:
> >

> Why is this circuit set up to do this?

If the long piece of wire from the solenoid to the master switch
should happen to short to ground anywhere, it would keep the solenoid
activated, instead of blowing fuses as it would if you were switching
the +12. It was the safest, most reliable design at a time when
today's clocks were unheard of.
--
Gene Seibel
Hangar 131 - http://pad39a.com/gene/plane.html
Because I fly, I envy no one.

1. Almost universally, aircraft master switches are set up with one side of the
switch grounded to the airframe and the other side of the switch to the "cold"
side of the master switch relay (or solenoid, if you prefer). The "hot" side
of the relay goes directly to the battery (+) lead. When you turn the master
switch on, it provides a ground for the relay and thus pulls in the relay
contacts providing you battery juice to the rest of the airplane.

2. The regs allow a small circuit breaker to also go directly to the battery
(+) terminal for such things as clocks, radio memory, and other things that need
juice full-time. As I vaguely recall without pulling out the regs, you can have
up to a 5 amp breaker, but it needs to be VERY near the battery box to minimize
the amount of unprotected wire running about the airframe. Most of us use a
small L-bracket mounted directly to the battery box and a VERY well insulated
short wire from the hot side of the master switch relay to the breaker.

3. Do yourself a favor. Get a small terminal strip (NEVER would I recommend
the Radio Shack #274-656 @ 2 for $1.69 for a certificated airplane) and mount
the terminal strip somewhere between the firewall and the instrument panel in an
easily accessable spot. Wire one lead of the terminal strip to airframe ground
and the other lead of the terminal strip to a wire going back to the
aforementioned keep-alive breaker on the battery box. Then wire the clock to
the terminal strip. Trust me, you will some day need to connect a radio or
other device to the keep-alive breaker and it is a hell of a lot easier to run
two wires to a terminal strip than another wire all the way back to the
tailfeathers battery.

Jim
Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

Ah, HA!

Thanks, Aaron.

"Aaron Coolidge" > wrote in message
...
> Jon Woellhaf > wrote:
> :> Jay wrote, "Apparently the Piper master switch -- on the hot side
only --
> :> "powers down" after 15 seconds! Some solenoid somewhere gets thrown,
> :> grounding the circuit and killing power to the hot side of the master
> :> switch."
>
> : What?! I'd love to see a diagram of that circuit.
>
> The Piper master switch does no such thing. The piper master switch
supplies
> GROUND to the master solenoid. Whne the switch is off, no current is
flowing
> through the solenoid windings, and the master switch appears to have +12V
> battery connected to it - which it does - through the solenoid windings.
> When you flip the master on, it grounds the wire from the solenoid that
> previously appeared to have +12V battery on it. (Just like the dome light
> switch on every car except for Fords.)
>
> ASCII schematic:
>
> (+ Battery)---(solenoid)-----(master switch)-----(- battery)
>
> --
> Aaron Coolidge
>

Newps > wrote:
: So why dis Piper wire it that way? Cessna has a separate circuit, the keep
: alive circuit for what ever piece of equipment that needs it, that is wired
: to the hot side of the master contactor. There is a fuse right next to the
: master contactor for this circuit.

I think Piper did it this way because the battery is in the tailcone, not
just on the other side of the firewall, and wiring the system like this
minimizes the potential damage if the "master contactor" wire should short
out.

As other have pointed out, Cessna airplanes have a small fuse right next to
the battery to run the clock and the hobbs meter (why the hobbs? so that
the renter can't fly around with the master "off" and run up no time!).
My airplane also has a small fuse next to the battery, that is wired up to
the white dome light so that I can have that light on with the master off.
I have an Astrotech clock that's powered by an internal 'AAA' battery, so
that's not wired up to anything.

--
Aaron Coolidge

$9 kitchen timer with velcro on the back. Big huge numbers. Loud alarm.
Homemade wooden wedge attached to panel of my Cherokee to fix it at a nice
viewable angle. Another strip of velcro on my knee board for when I fly
other planes. Works great. Less filling.



"Jay Honeck" > wrote in message
news:wRurc.92436$iF6.8041834@attbi_s02...
> > Jay... I have a cheaper alternative.. I carry my "ships clock" on my
> wrist..
>
> Funny, that's what one of the wise old heads on the field said, while
Darryl
> was poking around: "Why in HELL do you need an electric CLOCK, for
> Chrissakes? Doncha got a WATCH?"
>
> :-)
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"

Newps wrote:
>
> So why dis Piper wire it that way?

Well, if you re-read Jay's original post, you'll see that Piper didn't wire the clock
that way. Jay's mechanic did. Jay's A&P could hook things up the way keep-alives are
wired on my Maule and my old 150, but that would require running the wire through the
firewall to the starter solenoid. Some A&Ps are reluctant to run new wiring through
the firewall.

So. Jay. Your mech is reluctant to run a wire all the way back to the battery.
Where's this master solenoid? That will be hooked directly to the battery. Maybe it's
convenient to hook up to that.

George Patterson
I childproofed my house, but they *still* get in.

Jim Weir > wrote:
<snip>
> the terminal strip somewhere between the firewall and the instrument panel in an
> easily accessable spot. Wire one lead of the terminal strip to airframe ground
> and the other lead of the terminal strip to a wire going back to the
> aforementioned keep-alive breaker on the battery box. Then wire the clock to
> the terminal strip. Trust me, you will some day need to connect a radio or
> other device to the keep-alive breaker and it is a hell of a lot easier to run
> two wires to a terminal strip than another wire all the way back to the
> tailfeathers battery.

Exactly! I don't understand why Jay or Jay's A&P is fooling with the
master switch or anything presently under the panel (unless he has an
existing memory keep-alive). If he doesn't take your advice and use the
terminal strip, he should atleast go directly to the battery (thru a fuse
or circuit breaker.

--- Jay


--
__!__
Jay and Teresa Masino ___(_)___
http://www2.ari.net/jmasino ! ! !
http://www.oceancityairport.com
http://www.oc-adolfos.com

"Aaron Coolidge" > wrote in message
...

> I think Piper did it this way because the battery is in the tailcone, not
> just on the other side of the firewall,

Many Cessna's, including my 182, have the battery behind the baggage
compartment.


> As other have pointed out, Cessna airplanes have a small fuse right next
to
> the battery to run the clock and the hobbs meter

I found this out the hard way. I had a leak in the rear window. It rained
and the water ran down and onto the master contactor, shorting it out and
turning it on, rendering the master switch on the panel useless. I learned
from this that my battery will run the turn coordinator and some instrument
lights for about 19 hours before it goes dead.

The piper master connects the low side of the master solenoid winding to
ground. If you wired the clock to the 'high' side of the master switch, you
are powering the clock thorugh the master solenoid winding when the master
switch is off, and turning off the power to the clock (grounding the V+ clock
input) when the master is 'pn'. The clock must have a capacitor that keeps
it alive for about 15 sec after power is gone. Try hooking it up to a 12
battery, then removing power. I bet it stays on for 15 sec.

Jon Woellhaf wrote:

> Jay wrote, "Apparently the Piper master switch -- on the hot side only --
> "powers down" after 15 seconds! Some solenoid somewhere gets thrown,
> grounding the circuit and killing power to the hot side of the master
> switch."
>
> What?! I'd love to see a diagram of that circuit.
>
> Jon

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

The purpose of that circuit is to turn on the master solenoid. That is
that way so that there is only one wire needed to control the master
solenoid. Otherwise, you'd need an always hot wire going to the panel
throught the master switch and then back to the solenoid (which needs two
wires). It also has an advantage of restricting battery voltage to the
battery box area when the master is in the off position so that there is
less chance of an electrical short that can't be isolated by turning off
the master.



Jay Honeck wrote:

> > ASCII schematic:
> >
> > (+ Battery)---(solenoid)-----(master switch)-----(- battery)
>
> Thanks, Aaron.
>
> For us electrical dimwits, can you explain the purpose of this circuit?
>
> Also, why is there a 7-second delay after turning the master switch on?
>
> Here's how it works:
>
> 1. The clock is connected to the "hot" side of the master.
> 2. It works fine with master "off"
> 3. Turn Master Switch "on" -- works fine for seven seconds.
> 4. At seven seconds, the clock goes out.
> 5. Turn Master Switch "off" and the clock comes back on.
>
> What's going on? Why is this circuit set up to do this?
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

The master solenoid is right next to the battery box. Running that extra wire is a pain
in a PA-28, it involves pulling off the left interior sidewall. Piper didn't put it in
there originally because the airplane did not have anything outside of the battery box
that needed always on power (the clock was a mechanical clock).

"G.R. Patterson III" wrote:

> Newps wrote:
> >
> > So why dis Piper wire it that way?
>
> Well, if you re-read Jay's original post, you'll see that Piper didn't wire the clock
> that way. Jay's mechanic did. Jay's A&P could hook things up the way keep-alives are
> wired on my Maule and my old 150, but that would require running the wire through the
> firewall to the starter solenoid. Some A&Ps are reluctant to run new wiring through
> the firewall.
>
> So. Jay. Your mech is reluctant to run a wire all the way back to the battery.
> Where's this master solenoid? That will be hooked directly to the battery. Maybe it's
> convenient to hook up to that.
>
> George Patterson
> I childproofed my house, but they *still* get in.

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

No, it is under the back seat right next to the battery box

Judah wrote:

> FIs the Master solenoid closer to the front of the panel than the Battery?

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

Oh. At that point he may as well wire it up properly then...

Ray Andraka > wrote in
:

> No, it is under the back seat right next to the battery box
>
> Judah wrote:
>
>> Is the Master solenoid closer to the front of the panel than the
>> Battery?
>
> --
> --Ray Andraka, P.E.
> President, the Andraka Consulting Group, Inc.
> 401/884-7930 Fax 401/884-7950
> email
> http://www.andraka.com
>
> "They that give up essential liberty to obtain a little
> temporary safety deserve neither liberty nor safety."
> -Benjamin Franklin, 1759
>
>
>

> Jim Weir > wrote:
> <snip>
> > the terminal strip somewhere between the firewall and the instrument panel
> > in an
> > easily accessable spot. Wire one lead of the terminal strip to airframe
> > ground
> > and the other lead of the terminal strip to a wire going back to the
> > aforementioned keep-alive breaker on the battery box. Then wire the clock
> > to
> > the terminal strip. Trust me, you will some day need to connect a radio or
> > other device to the keep-alive breaker and it is a hell of a lot easier to
> > run
> > two wires to a terminal strip than another wire all the way back to the
> > tailfeathers battery.

Do you also want some sort of current limiting resistor in line with
the clock wire?
When the solenoid is activated, doesn't it draw a slug of current?
I would hate to destroy the clock electronics as a result of current
spikes.

EDR >
shared these priceless pearls of wisdom:

->
->Do you also want some sort of current limiting resistor in line with
->the clock wire?

Not unless the manufacturer of the clock put such a device in the installation
instructions. I can't tell you how many hours I've spent troubleshooting
problems that people "engineered" into their own systems by "making it better"
than the designer intended.

If a company manufactures aircraft clocks (or radios, or other electrical
devices) it is understood that there are going to be times when a spike comes
down the path. We all design in protective circuitry or some sort of spike
limiter/crowbar to limit the nasties. There are tens of thousands of articles
written on surge/spike suppression and there are tens of thousands of ways of
designing in that protection. What we CANNOT design in is protection from
somebody putting in a resistor or some other device that honks up something that
we did not contemplate.



->When the solenoid is activated, doesn't it draw a slug of current?

Not really. It is just another relay, albeit a pretty good sized one. And, it
is VERY close to the battery and wired with VERY heavy wire. Close and heavy
minimizes the inductance, and since the induced voltage is equal to L * di/dt,
and with that huge spike suppression capacitor called a battery on the line, the
spike should be relatively benign. NOTHING to compare to a starter motor firing
up.


->I would hate to destroy the clock electronics as a result of current
->spikes.

And the clock manufacturer would LONG since have been out of business if his
devices didn't take spikes into account.

Jim

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

Jay,
what's wrong with a $20 Timex?

Shawn
"Jay Honeck" > wrote in message
news:lEurc.36031$gr.3583857@attbi_s52...
> So I picked up this nifty Davtron digital electric clock/timer at Sun N
Fun.
> It's exactly the same model I had in my Warrior (Model 800), and I found a
> good price for it. (Roughly 4 times what it's really worth -- a bargain
in
> aviation!) Our wind-up clock had become sporadic in cold weather, and I
> kept forgetting to wind it anyway...
>
> My A&P took one look at the box and said "This will be a snap to install!"
> This should have set off warning alarms right away, but it didn't. We
> decided to do it at the annual, when everything was already ripped apart
> anyway.
>
> So, after most of the annual was complete, Darryl (the junior A&P in our
> 2-man shop) dug into it. As expected, it turned out to be a real
> son-of-a-bitch getting at the backside of the panel. I ended up standing
on
> my head under the panel, holding the clock in place with the very tips of
my
> fingers, while Darryl carefully dropped the tiny little retaining screws
> onto my belly, over and over again. It was fun! Really!
>
> Eventually, through sheer persistence, he got the damned screws threaded
in.
> Then the real fun began -- wiring! The directions clearly called for the
> dimmer control wire to be connected to one of the panel lights, and the
hot
> lead to go directly to the battery. Unfortunately the battery was in the
> way back of the plane -- not exactly handy -- so Darryl decided to wire it
> into the hot side of the master switch.
>
> This made sense to me -- which, again, should have set off warning bells
in
> my head, but didn't -- as the master switch was a heckuva lot closer than
> the battery.
>
> So I picked the plane up today, after reassembling the last little bits
and
> pieces. Everything looked great, the engine fired up easily, I taxied
about
> 40 yards -- and the clock blinked out and died....
>
> Immediately spinning the plane around, I shut the engine and master
down --
> and the clock came back to life! So, I turned the master switch back on,
> and *poof* -- 15 seconds later, the clock went blank.
>
> What the hell!?
>
> Darryl was completely stumped, and a huddle of wise old airport bums
> immediately assembled. It was obvious that hooking up to the "hot" side
of
> the master switch was NOT giving us continuous power -- but why?
>
> No one knew, and I had to get back to the hotel. I took the plane back to
> my hangar, and left the wise men standing there scratching their heads.
>
> As soon as I got back to the inn, I called Davtron. Describing the
symptoms
> to them, they immediately knew the problem. Apparently the Piper master
> switch -- on the hot side only -- "powers down" after 15 seconds! Some
> solenoid somewhere gets thrown, grounding the circuit and killing power to
> the hot side of the master switch.
>
> They said I had two choices: 1) Run the power directly to the battery,
> clear in the back of the plane, or 2) send the clock into Davtron, for
free
> installation of a battery back up. This battery allows the clock to be
> connected to the avionics master, rather than a "hot" wire.
>
> I immediately called Darryl, and gave him the options. He has agreed to
> fix the problem on Monday, whatever it takes, free of charge. Rather
than
> take the thing out, send it to California, and reinstall it -- he's opted
to
> run the wire to the battery...
>
> Live and learn -- who'd ever think that installing a gol-danged CLOCK
would
> be so hard?
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

> what's wrong with a $20 Timex?

Well, as my airplane is back in the shop, with the interior torn out once
again, just so they can run a damned wire back to the battery, I have to ask
myself the very same question.

The worst part is knowing that the odds of them breaking SOMETHING else
while they are working on the plane are at least 50/50...probably higher.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay Honeck > wrote:
> Well, as my airplane is back in the shop, with the interior torn out once
> again, just so they can run a damned wire back to the battery, I have to ask
> myself the very same question.
> The worst part is knowing that the odds of them breaking SOMETHING else
> while they are working on the plane are at least 50/50...probably higher.

Plus, the fact that this VERY simple instalation gave your A&P trouble
worries me (and should worry you). He should have known how this
electrical system works without even looking at the wiring diagram. It's
not exactly a "state secret" that clock power, and radio memory keep
alives, generally have to have a wire run to the battery. You'd better
keep an eye on this guy.

--- Jay


--
__!__
Jay and Teresa Masino ___(_)___
http://www2.ari.net/jmasino ! ! !
http://www.oceancityairport.com
http://www.oc-adolfos.com

"Jay Honeck" > writes:

>> what's wrong with a $20 Timex?
>
> Well, as my airplane is back in the shop, with the interior torn out once
> again, just so they can run a damned wire back to the battery, I have to ask
> myself the very same question.

Let's hear it for wind-up clocks, even if I did just pay the equivalent
cost of a new digital clock to get mine repaired.

--
Matt Emerson (1963 Mooney M20D)

> Plus, the fact that this VERY simple instalation gave your A&P trouble
> worries me (and should worry you). He should have known how this
> electrical system works without even looking at the wiring diagram. It's
> not exactly a "state secret" that clock power, and radio memory keep
> alives, generally have to have a wire run to the battery. You'd better
> keep an eye on this guy.

Absolutely.

This A&P is a 60 year old, retired grocery store manager, working as an
"apprentice" with my favorite A&P, a "master mechanic" with 30+ years
experience. He just got his A&P license this past winter, but has been
working around airplanes for many years. (He owned and operated an FBO
before going into business with his best friend, the master mechanic, and is
a CFI who owned a Bonanza for many years.)

He's a helluva nice guy, very careful and thorough about most things -- but
he obviously didn't know what the heck he was doing with this clock.

The upside: He's fixing it on his nickel. The downside: Every time you
take something apart, you risk breaking something else.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Why didn't you just get the clock with the battery pack attached?

Mike
MU-2


"Jay Honeck" > wrote in message
news:Gnrsc.108280$536.19076605@attbi_s03...
> > Plus, the fact that this VERY simple instalation gave your A&P trouble
> > worries me (and should worry you). He should have known how this
> > electrical system works without even looking at the wiring diagram.
It's
> > not exactly a "state secret" that clock power, and radio memory keep
> > alives, generally have to have a wire run to the battery. You'd better
> > keep an eye on this guy.
>
> Absolutely.
>
> This A&P is a 60 year old, retired grocery store manager, working as an
> "apprentice" with my favorite A&P, a "master mechanic" with 30+ years
> experience. He just got his A&P license this past winter, but has been
> working around airplanes for many years. (He owned and operated an FBO
> before going into business with his best friend, the master mechanic, and
is
> a CFI who owned a Bonanza for many years.)
>
> He's a helluva nice guy, very careful and thorough about most things --
but
> he obviously didn't know what the heck he was doing with this clock.
>
> The upside: He's fixing it on his nickel. The downside: Every time you
> take something apart, you risk breaking something else.
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

> Why didn't you just get the clock with the battery pack attached?

That's what Davtron asked me.

Of course, the guy at Sun N Fun never asked what kind of plane I had, or
showed me any options. ( A clock is a clock, right?) I just picked the
one that looked exactly like the one I had in my Warrior -- it never dawned
on me to get anything else.

I guess I figured hooking up a clock would be no big deal. For a brief
moment I forgot I was in "aviation-land" -- where logic is perennially stood
on its head, and NOTHING is easy...
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

That's why manufactures make instructions


"Jay Honeck" > wrote in message
news:lEurc.36031$gr.3583857@attbi_s52...
> So I picked up this nifty Davtron digital electric clock/timer at Sun N
Fun.
> It's exactly the same model I had in my Warrior (Model 800), and I found a
> good price for it. (Roughly 4 times what it's really worth -- a bargain
in
> aviation!) Our wind-up clock had become sporadic in cold weather, and I
> kept forgetting to wind it anyway...
>
> My A&P took one look at the box and said "This will be a snap to install!"
> This should have set off warning alarms right away, but it didn't. We
> decided to do it at the annual, when everything was already ripped apart
> anyway.
>
> So, after most of the annual was complete, Darryl (the junior A&P in our
> 2-man shop) dug into it. As expected, it turned out to be a real
> son-of-a-bitch getting at the backside of the panel. I ended up standing
on
> my head under the panel, holding the clock in place with the very tips of
my
> fingers, while Darryl carefully dropped the tiny little retaining screws
> onto my belly, over and over again. It was fun! Really!
>
> Eventually, through sheer persistence, he got the damned screws threaded
in.
> Then the real fun began -- wiring! The directions clearly called for the
> dimmer control wire to be connected to one of the panel lights, and the
hot
> lead to go directly to the battery. Unfortunately the battery was in the
> way back of the plane -- not exactly handy -- so Darryl decided to wire it
> into the hot side of the master switch.
>
> This made sense to me -- which, again, should have set off warning bells
in
> my head, but didn't -- as the master switch was a heckuva lot closer than
> the battery.
>
> So I picked the plane up today, after reassembling the last little bits
and
> pieces. Everything looked great, the engine fired up easily, I taxied
about
> 40 yards -- and the clock blinked out and died....
>
> Immediately spinning the plane around, I shut the engine and master
down --
> and the clock came back to life! So, I turned the master switch back on,
> and *poof* -- 15 seconds later, the clock went blank.
>
> What the hell!?
>
> Darryl was completely stumped, and a huddle of wise old airport bums
> immediately assembled. It was obvious that hooking up to the "hot" side
of
> the master switch was NOT giving us continuous power -- but why?
>
> No one knew, and I had to get back to the hotel. I took the plane back to
> my hangar, and left the wise men standing there scratching their heads.
>
> As soon as I got back to the inn, I called Davtron. Describing the
symptoms
> to them, they immediately knew the problem. Apparently the Piper master
> switch -- on the hot side only -- "powers down" after 15 seconds! Some
> solenoid somewhere gets thrown, grounding the circuit and killing power to
> the hot side of the master switch.
>
> They said I had two choices: 1) Run the power directly to the battery,
> clear in the back of the plane, or 2) send the clock into Davtron, for
free
> installation of a battery back up. This battery allows the clock to be
> connected to the avionics master, rather than a "hot" wire.
>
> I immediately called Darryl, and gave him the options. He has agreed to
> fix the problem on Monday, whatever it takes, free of charge. Rather
than
> take the thing out, send it to California, and reinstall it -- he's opted
to
> run the wire to the battery...
>
> Live and learn -- who'd ever think that installing a gol-danged CLOCK
would
> be so hard?
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

His Nickle? he already got your money for doing it wrong.


"Jay Honeck" > wrote in message
news:Gnrsc.108280$536.19076605@attbi_s03...
> > Plus, the fact that this VERY simple instalation gave your A&P trouble
> > worries me (and should worry you). He should have known how this
> > electrical system works without even looking at the wiring diagram.
It's
> > not exactly a "state secret" that clock power, and radio memory keep
> > alives, generally have to have a wire run to the battery. You'd better
> > keep an eye on this guy.
>
> Absolutely.
>
> This A&P is a 60 year old, retired grocery store manager, working as an
> "apprentice" with my favorite A&P, a "master mechanic" with 30+ years
> experience. He just got his A&P license this past winter, but has been
> working around airplanes for many years. (He owned and operated an FBO
> before going into business with his best friend, the master mechanic, and
is
> a CFI who owned a Bonanza for many years.)
>
> He's a helluva nice guy, very careful and thorough about most things --
but
> he obviously didn't know what the heck he was doing with this clock.
>
> The upside: He's fixing it on his nickel. The downside: Every time you
> take something apart, you risk breaking something else.
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

> You'd better
>keep an eye on this guy.
>

Yeah, I said the same thing back during the panel light problems....

MC > writes:

>> Jay wrote, "Apparently the Piper master switch -- on the hot side only --
>> "powers down" after 15 seconds! Some solenoid somewhere gets thrown,
>> grounding the circuit and killing power to the hot side of the master
>> switch."
>>
>> What?! I'd love to see a diagram of that circuit.
>
>Me to.
>That sounds like a bizzare system !
Whattheysaid...

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

Easy way to do this is two diodes. Common is the clock in.

One from the master switch hot; the other from the avionics hot.

When the master is off, that 13.8v supplies the clock. When it's
on, the avionics bus is hot.

No wire-stringing needed.
--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433