Battery Contactor Diode?

[Skrud]

What is the correct type of diode (p/n) to put across a garden-variety
battery contactor to prevent the inductive spike?

[Rob Turk[_1_]]

"Skrud" > wrote in message
.. .
> What is the correct type of diode (p/n) to put across a garden-variety
> battery contactor to prevent the inductive spike?
>

Something like a 1N4004 (1A, 400V) should do just fine.

Rob

[karel]

"Rob Turk" > wrote in message
...
> "Skrud" > wrote in message
> .. .
>> What is the correct type of diode (p/n) to put across a garden-variety
>> battery contactor to prevent the inductive spike?
>>
>
> Something like a 1N4004 (1A, 400V) should do just fine.

Yep that what's I thought.
But doesn't it depend on the size of garden?
KA

[RST Engineering]

"karel" > wrote in message
...
>
> "Rob Turk" > wrote in message
> ...
>> "Skrud" > wrote in message
>> .. .
>>> What is the correct type of diode (p/n) to put across a garden-variety
>>> battery contactor to prevent the inductive spike?
>>>
>>
>> Something like a 1N4004 (1A, 400V) should do just fine.
>
> Yep that what's I thought.
> But doesn't it depend on the size of garden?

Not really. The size of the chip above the 1N4003 is fairly hefty and
constant as opposed to the size down around the 1N4001. You aren't worried
about carrying reverse currents of an amp or so; what you are concerned with
is single-pulse forward currents of hundreds of amps for a microsecond. The
1N4004 ought to do you just fine until you get to the current level for a
contactor for a railroad diesel engine {;-)


Jim

[Joaquin Murrieta]

On Sun, 03 Sep 2006 13:40:12 GMT, "Skrud" >
wrote:

>What is the correct type of diode (p/n) to put across a garden-variety
>battery contactor to prevent the inductive spike?
>

Why wouldn't you use a capacitor?

Joaquin

[karel]

"RST Engineering" > wrote in message
...
>
> "karel" > wrote in message
> ...
>>
>> "Rob Turk" > wrote in message
>> ...
>>> "Skrud" > wrote in message
>>> .. .
>>>> What is the correct type of diode (p/n) to put across a garden-variety
>>>> battery contactor to prevent the inductive spike?
>>>>
>>>
>>> Something like a 1N4004 (1A, 400V) should do just fine.
>>
>> Yep that what's I thought.
>> But doesn't it depend on the size of garden?
>
> Not really. The size of the chip above the 1N4003 is fairly hefty and
> constant as opposed to the size down around the 1N4001.

Never knew this - thank you!

> You aren't worried about carrying reverse currents of an amp or so; what
> you are concerned with is single-pulse forward currents of hundreds of
> amps for a microsecond. The 1N4004 ought to do you just fine until you
> get to the current level for a contactor for a railroad diesel engine {;-)

Yep indeed!
KA

[ELIPPSE]

Skrud wrote:
> What is the correct type of diode (p/n) to put across a garden-variety
> battery contactor to prevent the inductive spike?
'Depends. If the circuit would have adverse effect from a delay in
dropping out, it would be better to use a zener diode or transient
suppressor with appropriate voltage and current ratings. A diode across
a coil causes the current to flow longer than it would in an open
circuit, and so delays the drop-out of a relay. That may not be desired
where a motor is controlled by the relay, which would then run longer
and, perhaps, over-shoot a limit switch.

[ELIPPSE]

Skrud wrote:
> What is the correct type of diode (p/n) to put across a garden-variety
> battery contactor to prevent the inductive spike?
It's also a good idea to have the diode at the load, rather than at the
switch. This keeps the diode current circulating only at the load, and
not through the wiring, where it can induce transients in nearby
wiring. This, especially, if the wiring is not twisted pair, but
instead uses the airframe as one of the conductors. With this, there is
only one wire carrying the current, so it acts as an antenna, radiating
into nearby wiring both electromagnetically and electrostatically.
Twisted pair wiring minimizes these effects, since the magnetic fields
from the opposite-direction currents cancels.

[[email protected]]

Joaquin Murrieta wrote:
> On Sun, 03 Sep 2006 13:40:12 GMT, "Skrud" >
> wrote:
>
> >What is the correct type of diode (p/n) to put across a garden-variety
> >battery contactor to prevent the inductive spike?
> >
>
> Why wouldn't you use a capacitor?
>
> Joaquin

A capacitor has limited capacity, and as Jim Weir pointed out,
we're talking about a lot of current here, even though it's a brief
pulse. The diode shorts the current during the inductive spike
generated when the master switch ( or starter switch) is opened,
keeping that spike from entering the rest of the aircraft's electical
system. A capacitor would store some of it, but there'd be enough left
over to cause trouble. A capacitor thus charged also keeps the
contactor closed for some time after shutoff as it discharges through
the coil.
I have measured a 600 volt spike across the master contactor
coil. Gives a person a really good jolt if he's touching the terminals
at the time. Makes one respectful of the system, and makes him more
aware of the need to shut off avionics before shutting off the master.
We can't really rely on that diode always being in good shape.
A Zener diode won't work here any better than a switching diode.
We need a diode that allows forward current flow for a very short
period, while preventing reverse flow during normal operation. A Zener
is designed to break down at a specific reverse voltage, and the only
reverse voltage this application offers is the usual 14 volts or so
during aircraft operation.

Dan

[Scott[_1_]]

Nope, not really a concerning factor. Any of the "garden variety"
diodes in the 1N400X series should be fine. Just be sure to put the
cathode to the +12 or +24 volt side of the contactor coil and the anode
to the ground side (assuming a negative ground system).

Scott


karel wrote:
> "Rob Turk" > wrote in message
> ...
>
>>"Skrud" > wrote in message
.. .
>>
>>>What is the correct type of diode (p/n) to put across a garden-variety
>>>battery contactor to prevent the inductive spike?
>>>
>>
>>Something like a 1N4004 (1A, 400V) should do just fine.
>
>
> Yep that what's I thought.
> But doesn't it depend on the size of garden?
> KA
>
>

[Morgans[_4_]]

"Scott" > wrote in message
.. .
> Nope, not really a concerning factor. Any of the "garden variety"
> diodes in the 1N400X series should be fine. Just be sure to put the
> cathode to the +12 or +24 volt side of the contactor coil and the anode
> to the ground side (assuming a negative ground system).

I am not very good with the electron understanding, but I would be grateful
to understand this whole discussion.

Is the cathode normally the downstream side of the diode? What does the
installation like this, do, to help with the current spike?
--
Jim in NC

[Morgans[_4_]]

"Morgans" > wrote
>
> I am not very good with the electron understanding, but I would be
grateful
> to understand this whole discussion.
>
> Is the cathode normally the downstream side of the diode? What does the
> installation like this, do, to help with the current spike?

Oh, I also want to add, that if Jim Weir responds, will someone reply to the
post with his entire post quoted?

For some reason, my ISP seems to have "blacklisted" his ISP, so the only
way I see his posts is in a response.

Also, to say I don't understand electrons, is a huge understatement! <g>
--
Jim in NC

[RST Engineering]

"Morgans" > wrote in message
...
>
> "Scott" > wrote in message
> .. .

>> Nope, not really a concerning factor. Any of the "garden variety"
>> diodes in the 1N400X series should be fine. Just be sure to put the
>> cathode to the +12 or +24 volt side of the contactor coil and the anode
>> to the ground side (assuming a negative ground system).

Scott, at and above the 1N4004, the chip inside the case is physically more
robust and will take a spike of current a little better than, say, a 1N4001.




>
> I am not very good with the electron understanding, but I would be
> grateful
> to understand this whole discussion.
>
> Is the cathode normally the downstream side of the diode? What does the
> installation like this, do, to help with the current spike?


Jim, as you know, a diode conducts current in one direction and blocks it
from conducting in the other direction. A positive voltage on the anode
forward biases the diode and the voltage will appear as a positive voltage
(less some small conduction drop of a volt or so) at the cathode. A
negative voltage on the anode will reverse bias the diode and it will not
appear as a negative voltage at the cathode.

Likewise, a negative voltage at the cathode will appear as a negative
voltage at the anode.

When a coil has a collapsing field, it produces a spike of energy as the
field attempts to keep the current through the coil constant. THis large
negative spike can and will cause some of the aircraft electronics to fail
catastrophically. One way of making sure that negative spike doesn't kill
the avionics is to shunt it to ground through a forward biased diode. That
way the most that can sneak through is a volt or so as opposed to several
hundred volt spikes without the diode. How do you forward bias a diode with
a negative voltage? You connect the CATHODE to the "hot" +12 volt terminal
of the coil and the ANODE to ground. THe negative spike is effectively
clipped at a volt or thereabouts.

Jim

[RST Engineering]

Bummer. ANd I just switched ISPs also. I'm now using wildblue and if
you've got wildblue blocked, you won't get any of us using satellite ISPs.

Jim

>
> For some reason, my ISP seems to have "blacklisted" his ISP, so the only
> way I see his posts is in a response.
> --
> Jim in NC
>

[Scott[_1_]]

Hi Jim,
Schematically, the cathode is the bar and the anode is the arrow part.

With the diode connected with its cathode to the positive voltage and
its anode connected to ground, it is reverse biased and looks like an
open circuit during normal operation. When the contactor relay (master
solenoid) is turned off, the collapsing magnetic field will generate a
field of opposite polarity (the voltage spike we are talking about) such
that the side of the coil that is connected to the +12V bus will now be
at a large NEGATIVE voltage, putting the cathode of the diode more
negative than its anode and it will now conduct. The voltage across a
conducting diode is about 0.7 Volts, so the spike will be limited to
about a -0.7V along the +12V bus in the aircraft. Without the diode,
hundreds of negative volts could be placed on the bus (for a short
period of time, in the milliseconds), but solid state devices don't get
along well with these high voltages, ESPECIALLY since it is opposite
polarity of what they are designed to operate at.

Scott


Morgans wrote:

> "Scott" > wrote in message
> .. .
>
>>Nope, not really a concerning factor. Any of the "garden variety"
>>diodes in the 1N400X series should be fine. Just be sure to put the
>>cathode to the +12 or +24 volt side of the contactor coil and the anode
>>to the ground side (assuming a negative ground system).
>
>
> I am not very good with the electron understanding, but I would be grateful
> to understand this whole discussion.
>
> Is the cathode normally the downstream side of the diode? What does the
> installation like this, do, to help with the current spike?

[Richard Riley[_1_]]

Morgans wrote:
> "Morgans" > wrote
> >
> > I am not very good with the electron understanding, but I would be
> grateful
> > to understand this whole discussion.
> >
> > Is the cathode normally the downstream side of the diode? What does the
> > installation like this, do, to help with the current spike?
>
> Oh, I also want to add, that if Jim Weir responds, will someone reply to the
> post with his entire post quoted?
>
> For some reason, my ISP seems to have "blacklisted" his ISP, so the only
> way I see his posts is in a response.
>
> Also, to say I don't understand electrons, is a huge understatement! <g>
> --
> Jim in NC


Try reading RAH here

http://groups.google.com/group/rec.aviation.homebuilt?lnk=gschg&hl=en

[Morgans[_2_]]

"Scott" > wrote in message
.. .
> Hi Jim,
> Schematically, the cathode is the bar and the anode is the arrow part.
>
> With the diode connected with its cathode to the positive voltage and
> its anode connected to ground, it is reverse biased and looks like an
> open circuit during normal operation. When the contactor relay (master
> solenoid) is turned off, the collapsing magnetic field will generate a
> field of opposite polarity (the voltage spike we are talking about) such
> that the side of the coil that is connected to the +12V bus will now be
> at a large NEGATIVE voltage, putting the cathode of the diode more
> negative than its anode and it will now conduct. The voltage across a
> conducting diode is about 0.7 Volts, so the spike will be limited to
> about a -0.7V along the +12V bus in the aircraft. Without the diode,
> hundreds of negative volts could be placed on the bus (for a short
> period of time, in the milliseconds), but solid state devices don't get
> along well with these high voltages, ESPECIALLY since it is opposite
> polarity of what they are designed to operate at.

Thanks, that was a clear explanation (I think <g>) of the type I was
looking for.

So the .7 volts in buss at the wrong polarity is not too much for all of the
electronics to deal with?
--
Jim in NC

[Scott[_1_]]

Correct!

Scott

Morgans wrote:

> "Scott" > wrote in message
> .. .
>
>>Hi Jim,
>>Schematically, the cathode is the bar and the anode is the arrow part.
>>
>>With the diode connected with its cathode to the positive voltage and
>>its anode connected to ground, it is reverse biased and looks like an
>>open circuit during normal operation. When the contactor relay (master
>>solenoid) is turned off, the collapsing magnetic field will generate a
>>field of opposite polarity (the voltage spike we are talking about) such
>>that the side of the coil that is connected to the +12V bus will now be
>>at a large NEGATIVE voltage, putting the cathode of the diode more
>>negative than its anode and it will now conduct. The voltage across a
>>conducting diode is about 0.7 Volts, so the spike will be limited to
>>about a -0.7V along the +12V bus in the aircraft. Without the diode,
>>hundreds of negative volts could be placed on the bus (for a short
>>period of time, in the milliseconds), but solid state devices don't get
>>along well with these high voltages, ESPECIALLY since it is opposite
>>polarity of what they are designed to operate at.
>
>
> Thanks, that was a clear explanation (I think <g>) of the type I was
> looking for.
>
> So the .7 volts in buss at the wrong polarity is not too much for all of the
> electronics to deal with?

[.Blueskies.]

If a switch is used to apply the 12 volts to the solenoid coil, and then the switch is opened, how does the voltage
generated during the collapse of the magnetic field get to the positive buss?


"Scott" > wrote in message .. .
: Hi Jim,
: Schematically, the cathode is the bar and the anode is the arrow part.
:
: With the diode connected with its cathode to the positive voltage and
: its anode connected to ground, it is reverse biased and looks like an
: open circuit during normal operation. When the contactor relay (master
: solenoid) is turned off, the collapsing magnetic field will generate a
: field of opposite polarity (the voltage spike we are talking about) such
: that the side of the coil that is connected to the +12V bus will now be
: at a large NEGATIVE voltage, putting the cathode of the diode more
: negative than its anode and it will now conduct. The voltage across a
: conducting diode is about 0.7 Volts, so the spike will be limited to
: about a -0.7V along the +12V bus in the aircraft. Without the diode,
: hundreds of negative volts could be placed on the bus (for a short
: period of time, in the milliseconds), but solid state devices don't get
: along well with these high voltages, ESPECIALLY since it is opposite
: polarity of what they are designed to operate at.
:
: Scott
:
:
: Morgans wrote:
:
: > "Scott" > wrote in message
: > .. .
: >
: >>Nope, not really a concerning factor. Any of the "garden variety"
: >>diodes in the 1N400X series should be fine. Just be sure to put the
: >>cathode to the +12 or +24 volt side of the contactor coil and the anode
: >>to the ground side (assuming a negative ground system).
: >
: >
: > I am not very good with the electron understanding, but I would be grateful
: > to understand this whole discussion.
: >
: > Is the cathode normally the downstream side of the diode? What does the
: > installation like this, do, to help with the current spike?

[[email protected]]

..Blueskies. wrote:
> If a switch is used to apply the 12 volts to the solenoid coil, and then the switch is opened, how does the voltage
> generated during the collapse of the magnetic field get to the positive buss?
>

The master solenoid coil has one terminal connected to the hot
(battery +) switching terminal, and the other goes to the master
switch, which grounds it when the switch is on. In this way, there's no
direct connection to the battery's positive terminal and no unloaded
feed line (with its risk of short-circuit and fire) leading into the
cabin.
When the master switch is turned off, the abrupt arresting of
the current causes a collapse of the magnetic field within the
solenoid's coil. This collapsing field tries to keep the current
flowing, and it is violent enough that the electrons will jump the gap
in the switch and complete the circuit to some degree. The spike is
extremely sudden and can be arcing across the switch's contact gap
before those contacts are very far apart. The electron flow is from
ground, through the partially open master switch contacts, through the
coil and into the solenoid's hot terminal, then through the solenoid's
big contacts (which are still closed during this almost instantaneous
event) and into the aircraft's electrical system. Any sensitive
electronic device (like an expensive radio) without its own internal
protection goes poof.

It's the same sort of process in the magneto. When the points
open, coil current is arrested and the collapse of the field causes a
big spike in the secondary winding, making spark plugs do their thing.
The points have a capacitor across them to absorb the initial surge
that tries to jump them as they open; an arc here would both burn the
points and prevent the really sudden arresting of the current that we
want to get the biggest jolt out of the magneto. The capacitor will
fill up, and by that time the points are too far apart for the curent
to jump them, so the arresting is more complete. That magneto won't
work worth a hoot without the capacitor (sometimes called condenser).
A diode would definitely not work in the magneto; we *want* a
big spike.
The diode across the solenoid's coil provides an easy path
from the solenoid's positive terminal back to it's negative, almost
completely draining off the spike and keeping it out of the system.

A long answer to a simple question, huh?

Dan

[Peter Dohm]

"RST Engineering" > wrote in message
...
>
> "Morgans" > wrote in message
> ...
> >
> > "Scott" > wrote in message
> > .. .
>
> >> Nope, not really a concerning factor. Any of the "garden variety"
> >> diodes in the 1N400X series should be fine. Just be sure to put the
> >> cathode to the +12 or +24 volt side of the contactor coil and the anode
> >> to the ground side (assuming a negative ground system).
>
> Scott, at and above the 1N4004, the chip inside the case is physically
more
> robust and will take a spike of current a little better than, say, a
1N4001.
>
>
>
>
> >
> > I am not very good with the electron understanding, but I would be
> > grateful
> > to understand this whole discussion.
> >
> > Is the cathode normally the downstream side of the diode? What does the
> > installation like this, do, to help with the current spike?
>
>
> Jim, as you know, a diode conducts current in one direction and blocks it
> from conducting in the other direction. A positive voltage on the anode
> forward biases the diode and the voltage will appear as a positive voltage
> (less some small conduction drop of a volt or so) at the cathode. A
> negative voltage on the anode will reverse bias the diode and it will not
> appear as a negative voltage at the cathode.
>
> Likewise, a negative voltage at the cathode will appear as a negative
> voltage at the anode.
>
> When a coil has a collapsing field, it produces a spike of energy as the
> field attempts to keep the current through the coil constant. THis large
> negative spike can and will cause some of the aircraft electronics to fail
> catastrophically. One way of making sure that negative spike doesn't kill
> the avionics is to shunt it to ground through a forward biased diode.
That
> way the most that can sneak through is a volt or so as opposed to several
> hundred volt spikes without the diode. How do you forward bias a diode
with
> a negative voltage? You connect the CATHODE to the "hot" +12 volt
terminal
> of the coil and the ANODE to ground. THe negative spike is effectively
> clipped at a volt or thereabouts.
>
> Jim
>
>
I totally missread the initial question when this thread first started, and
somehow I suspect that I may not have been the only reader who did so.

The battery contactor, usually operated by the master switch, should
normally be a trivial case with regard to voltage spikes the circuit is
protected by the battery. It does no harm to protect the circuit and, if
you want to be really anally retentive, you could measure the current drawn
by the coil of the contactor and size the diode for a little more current
than that. Once the current is flowing in an inductor, such as a contactor
coil, it will try to continue flowing at the same rate when you first turn
it off--which causes a voltage spike several times the normal operating
voltage. The protection diode simply allows the current to flow around in a
circle--through the diode and around back through the coil for a few
milliseconds until the resistance of the wiring in the coil uses up the
energy. Thus, presuming that the diode is located at the coil, the voltage
spike
should be limited to the forward voltage drop of the diode--usually about
six tenths of a volt.

With regard to possible damage to avionics, the contactors which have their
coils powered from the master buss (which presumably is activated by the
battery contactor) are the greater issue and all should be protected by
diodes--although capacitors may also work. Technically this is airframe
wiring and therefore in the mechanic's job description--so that is who to
see in the case of a certified aircraft.

Otherwise, nearly every EAA chapter has members who are or were mechanics as
well as members who are or were avionics technicians--and a couple of cups
of coffee with the three of you together, and maybee a couple of additional
members, will quickly solve a lot of problems. Remember that is a lot of
the original and continuing reason for chapters!

BTW the 1N400X series of diodes are 1 amp, and I believe that the next
common size is/was around 3 amps.

Regards,
Peter

[RST Engineering]

I could'na said it better myself.

Jim


> wrote in message
ups.com...


Any sensitive
> electronic device (like an expensive radio) without its own internal
> protection goes poof.

Poof. THat's a technical term. Stick around long enough and you'll get it.


>
That magneto won't
> work worth a hoot without the capacitor (sometimes called condenser).
>

Hoot's a technical term also. See answer above.

For the advanced student, do the calculation of the inductive reactance of
the magneto coil, the capacitive reactance of the magneto capacitor, the
frequency of the coil spark (RPM adjusted for seconds and the number of
cylinders) and see where the resonant frequency of that inductor and
capacitor are.

For the Master's thesis, factor in the resistance of the coil and see how
broad the Q of the resonant circuit is.

For the PhD dissertation, calculate the velocity of the flame front and
demonstrate the maximum cylinder pressure for two magnetos timed "x" degrees
apart.

Jim

Jim

[RST Engineering]

Please do not listen to this person. (S)he understands nothing about
reverse emf, nor about reverse voltage spikes. The forward current drawn by
the coil has no bearing on the multiple hundreds of amps that a reverse
polarity diode needs to conduct to keep a large NEGATIVE voltage spike from
frapping (that's a technical term, you'll get used to it) your radios.

Jim


> The battery contactor, usually operated by the master switch, should
> normally be a trivial case with regard to voltage spikes the circuit is
> protected by the battery. It does no harm to protect the circuit and, if
> you want to be really anally retentive, you could measure the current
> drawn
> by the coil of the contactor and size the diode for a little more current
> than that.

[Peter Dohm]

The reverse emf spike, just like any other emf, is measured in volts only.
The reverse current required to damage electronics is very small--that means
very very small. The coils of those little Ice Cube relays, with contact
ratings less than about 10 amps, usually have coil currents of less than
100ma; which is why 1N4004 diodes are so popular--and really overkill but
they weigh less than a gram. Larger relays, used to control more power, are
part of the mechanical airframe wiring and I continue to recommend that you
talk to one of the mechanics in your local chapter--one who also holds an
IA. There are more than enough small type certified aircraft in the rental
fleet to generate a highly reliable set of service bulletins with which a
mechanic with IA will be quite familiar. I also continue to recommend that
you include an electronics technician (preferably avionics) in the
conversation because all three on you, and any other builders who attend,
will come away with greater knowledge.

Disclaimer: Clearly, my technical knowledge is gravely wanting, as I have
no idea what "frapping" means.

Peter

"RST Engineering" > wrote in message
...
> Please do not listen to this person. (S)he understands nothing about
> reverse emf, nor about reverse voltage spikes. The forward current drawn
by
> the coil has no bearing on the multiple hundreds of amps that a reverse
> polarity diode needs to conduct to keep a large NEGATIVE voltage spike
from
> frapping (that's a technical term, you'll get used to it) your radios.
>
> Jim
>
>
> > The battery contactor, usually operated by the master switch, should
> > normally be a trivial case with regard to voltage spikes the circuit is
> > protected by the battery. It does no harm to protect the circuit and,
if
> > you want to be really anally retentive, you could measure the current
> > drawn
> > by the coil of the contactor and size the diode for a little more
current
> > than that.
>
>

[RST Engineering]

I couldn't agree more.

Jim Weir
Avionics Technician 1963 - 1967
Avionics Engineer 1967 - 20->
A&P, IA



"Peter Dohm" > wrote in message
...


I continue to recommend that you
> talk to one of the mechanics in your local chapter--one who also holds an
> IA. There are more than enough small type certified aircraft in the
> rental
> fleet to generate a highly reliable set of service bulletins with which a
> mechanic with IA will be quite familiar. I also continue to recommend
> that
> you include an electronics technician (preferably avionics) in the
> conversation because all three on you, and any other builders who attend,
> will come away with greater knowledge.

[Barnyard BOb]

"Peter Dohm" wrote:

>Disclaimer: Clearly, my technical knowledge is gravely wanting, as I have
>no idea what "frapping" means.
>
>Peter


Acronym....

**** FRAP Fluorescence Recovery After Photobleaching
**** FRAP Fire and Resource Assessment Program (California)
**** FRAP Facilitated Risk Analysis Process
**** FRAP Frame Relay Access Probe (Tylink)
**** FRAP Free Route Airspace Project (aeronautical)
*** FRAP Frenetic Random Activity Period (dog behavior
*** FRAP Fuel Rod Analysis Program
*** FRAP Fragmenting Payload
*** FRAP Flat Rate Access Promotion (Sprint)
*** FRAP Fleet Reliability Assessment Program
*** FRAP Facilitated Risk Analysis Procedure
* FRAP Frame Relay Access Point



American Heritage Dictionary -

Middle English frapen, to strike, from Old French fraper. 8o)


- Barnyard BOb -