Eagle ERC questions

[Enki-5]

        The FDN337N seems to not have the usual internal Zener between Gate
and Source for protection.
        Discovered that hard fact after 12 of them stopped working without
any reason.

        Mark Jordan


On 1 Aug 2008 at 5:42, Apptech wrote:

> >I looked for a fet with a lower gate voltage and wasn't
> >able to find one,
> > but I'll renew my search.
>
> Digiket etc
>
> FDN337 N Channel
> FDN338 P Channel
>
> & Zetex do some.
>
> & the lovely CES2310 - but probably Asia sources only.
>
> Try a series resistor in the supervisors input though.
> And, you can add as much load as you want to the output to
> increase the hysteresis as you wish.
> MAY need a small cap at superviror input when R used.
>
> MADE UP EXAMPLE ONLY
>
> Supervisor Iq = 10 uA.
> Superviros Ion = 100 uA.
> Transistor load = 100 uA.
>
> Using a 1k input resistor drops
>
> - 0.01V at 10 uA
> - 0.2 V with 100 uA IC + 100 uA transistor.
>
> If you decided you wanted more drop with output on you could
> either
>
> - Raise Rin to say 3k3
> or
> - Add a load resistor to output, or lower base drive R.
>
> Adding input R takes less current from battery when low.
>
>
>         Russell
>
>
>
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[Marcel Duchamp]

Did you notice the Vgs-max spec?

It's rather low: +/-8 volts.  And that is the *ABSOLUTE MAXIMUM* number.
  Something to watch for here would be ringing on the gate from trace
inductance feeding the gate capacitance.



Enki wrote:
> The FDN337N seems to not have the usual internal Zener between Gate
> and Source for protection.
> Discovered that hard fact after 12 of them stopped working without
> any reason.
>
> Mark Jordan

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[Cedric Chang-2]

Please send us an update when you achieve 99.999% success ( or sooner  
even )
cc

> On Jul 31, 2008, at 8:18 AM, Kevin wrote:
>
> On Thu, 31 Jul 2008, Walter Banks wrote:
>
> Some good brainstorming ideas !  Couple of issues I  should
> mention, I don't think I could get a camera looking down
> because of several large trees in the yard. Also, the yard
> is half level, the other half has a fall of probably 10 ft
> in 60 ft. So, one section is a steep hill. That may be
> a problem for a transmitter pole or sensor on top of the
> mower.
>
> I plan on making the mower as dumb as possible. I will have
> my computer perform the processing and relay course and
> direction to the mower through my wifi network or something
> similiar (zigbee, bluetooth, etc...).
>
> Thanks,
> Kevin
>
>

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[Cedric Chang-2]

An autonomous robot to push the mower.  Comes complete with beer/
chips ingesting orifice ( for energy ) , expandable thorax filled  
with beer/chips  ( for additional traction ).
cc

> On Jul 31, 2008, at 9:42 AM, Apptech wrote:
>
> - A wire grid would relatively easy to install ("mole plow"
> insertion) and probably as easy and accurate to drive as any
> other system.
>
> - A small UAV
>
> 1     flies a search grid looking for the mower.
> or
> 2     carries a camera which views the mover and targets for
> location.
>
> - A hot air ballon on a cable, powerd by a heater which
> allows it to always stay aloft ...
>
> - Hmm.
>   Mower.
>   Microphones mounted on the house ... .
>
> - An ultrasonic ranger on the mower identifies IR beacons
> and calculates their distance.
> or
> Utrasonic rangers detect the mowers location using a beacon
> on the mower.
>
> - A ...
>
> Sounds like fun.
>

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[John Coppens]

On Fri, 01 Aug 2008 03:42:12 +1200
Apptech <apptech@...> wrote:

> Sounds like fun.

For an acre, I suggest a couple of sheep. Low maintenance, no computer
needed, no cameras, IR, remote. Proven efficiency, much less noise. Added
advantage is the wool...

Of course, this would not be an [EE] solution.

John
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[Timothy Weber]

Some OP OP'ed:
>> I plan on making the mower as dumb as possible. I will have
>> my computer perform the processing and relay course and
>> direction to the mower through my wifi network or something
>> similiar (zigbee, bluetooth, etc...).

So, uh... belated reaction... Is your requirement really "Control
mower's position with 6 inches of precision" and not "Make it mow where
I want, but not where I don't want"?  I'm wondering if it might be
easier to do it Roomba-style and put markers around to define where you
*don't* want it to go, then send it on some kind of random walk that
will generally mow about everything.
--
Timothy J. Weber
http://timothyweber.org
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[Richard Prosser]

2008/8/2 Cedric Chang <cc@...>:
> An autonomous robot to push the mower.  Comes complete with beer/
> chips ingesting orifice ( for energy ) , expandable thorax filled
> with beer/chips  ( for additional traction ).
> cc
>

Or make it run on grass clippings?

RP
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[David Meiklejohn]

Richard Prosser wrote:
>
> 2008/8/2 Cedric Chang <cc@...>:
> > An autonomous robot to push the mower.  Comes complete with beer/
> > chips ingesting orifice ( for energy ) , expandable thorax filled
> > with beer/chips  ( for additional traction ).
>
> Or make it run on grass clippings?

That's called a "cow"...


David Meiklejohn
www.gooligum.com.au


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