This may or may not be considered OT. A PIC or AVR or Z8 or .... may very
well feature in the final design. At the moment the choice is open.
I have a demanding design requirement (to put it mildly) which others may
be interested in commenting on and/or cooperating with. The project is
currently at the "lets think of as many factors as we can" stage. The more
wild/useful/interesting/tangential ideas the better.
An amateur group is planning to send a small rocket to the Moon. Timescale
is :within the next 5 years".
Various ideas are being investigated to attract sponsorship and/or in their
own right.
One proposal to be investigated is to place a small transmitter (no
receiver) on the Lunar surface with the object of transmitting a very short
occasional signal over as long a period as reasonably possible. The module
is currently envisaged as a sphere of about 500 grams mass with batteries,
transmitter, cpu and aerial deployment system contained within. Current
thinking is for this to be ejected immediately prior to impact to avoid
being trapped by the probe at impact. This will not reduce the final
velocity.
The transmitter is estimated to be in the 1 - 10 watt range with a transmit
time of around 1 second and a duty cycle of "TBD". Batteries will be "best
available" for the requirement. Antenna will be low (possibly as high as
unity :-)) gain. Carrying and deploying an aerial, batteries, transmitter,
cpu and impact protection system within the available mass budget is an
interesting challenge.
- Impact velocity of the payload is to be as small as possible but a soft
landing "as we know it" may quite possibly not happen :-).
The transmitter module should survive as high an impact velocity as
possible. Survival at velocities of up to 100 metres/second (200 miles an
hour)(!!) may be possible.
Much lower velocities are aimed for.
- Temperatures on the Lunar surface range from a high of about 400 kelvins
(130 C) to a low of about 100 kelvins (-170 C).
Attempted operation during most of the lunar night would probably be
inadvisable :-).
Operation at even peak temperature may be possible with appropriate design.
Batteries able to survive these extremes may be difficult to source :-)
These conditions are quite demanding by normal standards.
IF the module survives impact the biggest challenge is liable to be
surviving the lunar nights.
Previous lunar equipment has often failed to last more than 1 or 2 nights
(each night is around 2 weeks long).
Problems include both the absolute temperatures and thermal cycling.
QUESTIONS:
1. Anyone interested even mildly please throw in as many even possibly
relevant ideas - the more the better. Off or on list as seems appropriate
2. Has anyone had practical (or theoretical) experience of very extreme
low temperature designs. (Not necessarily this low.)
3. Is anyone interested in ongoing discussion about this project - off
or on list as appropriate.
I will introduce the Lunaris project per se at a later date - there is lots
for interested people to do.
hi russell
>
> QUESTIONS:
>
> 1. Anyone interested even mildly please throw in as many even possibly
> relevant ideas - the more the better. Off or on list as seems appropriate
please, pick me, pick me. how about a teeny tiny seismograph using
that adx1202 chip and a hi-res adc, run it off a 16c84, oops,
need a memory chip, i2c, one of those 24c something or
others, ---gotta have some data to transmit, after all. surface
mount, probably size of quarter. p.s. i know nothing about surface
mount, but i have a toaster oven....
>
> 2. Has anyone had practical (or theoretical) experience of very extreme
> low temperature designs. (Not necessarily this low.)
>
> 3. Is anyone interested in ongoing discussion about this project - off
> or on list as appropriate.
>
> I will introduce the Lunaris project per se at a later date - there is lots
> for interested people to do.
>
> - Temperatures on the Lunar surface range from a high of about 400 kelvins
> (130 C) to a low of about 100 kelvins (-170 C).
> IF the module survives impact the biggest challenge is liable to be
> surviving the lunar nights.
> Previous lunar equipment has often failed to last more than 1 or 2 nights
> (each night is around 2 weeks long).
> Problems include both the absolute temperatures and thermal cycling.
Why not sustain a survivable internal temperature with chemical
exothermic reactions. The internal environment could be heavily
insulated and some body of fluid surround (either directly or in some
sort of bag) the electronics. The walls could be lined with sealed
tubes of a reacting fluid compound. At determined intervals (measured
temp vs time etc) a fuse could be burned that cut the end of the bag,
one wall of the bag could be Kynar (Piezo Co-Polymer)plastic that
will bend when energized (very low power) this will eject the fluid
into the main body of reacting fluid, a chemical process will take
place and the internal temp is monitored until another "dose" is
needed.
I have no idea what would be suitable chemicals but I am sure there
are plenty.
The other unopened bags could even act as a stirring source since
their respective piezo linings could act together in a synergesis of
stirring.
I have experimented with Kynar... it will do this.
A PIC controlling it of course.
Maybe I have gone mad?
Ohh look that mans gone mad!
_____________________________
Lance Allen
Technical Officer
Uni of Auckland
Psych Dept
New Zealand
_____________________________
Wait a minute...are you saying that Kynar (usually the insulation on wire
wrap wire) will bend under electrical stimulus??? How does it bend?
Does it shrink in length? Is it reproducable (i.e. is it a one-time
effect or will it recover when stimulus is removed)? You say the stimulus
is low power...what are we talking...+5v at how many milliamps??
I'd like to reproduce this effect...please describe your experimentation.
>Why not sustain a survivable internal temperature with chemical
>exothermic reactions. The internal environment could be heavily
>insulated and some body of fluid surround (either directly or in some
>sort of bag) the electronics. The walls could be lined with sealed
>tubes of a reacting fluid compound. At determined intervals (measured
>temp vs time etc) a fuse could be burned that cut the end of the bag,
>one wall of the bag could be Kynar (Piezo Co-Polymer)plastic that
>will bend when energized (very low power) this will eject the fluid
>into the main body of reacting fluid, a chemical process will take
>place and the internal temp is monitored until another "dose" is
>needed.
>I have no idea what would be suitable chemicals but I am sure there
>are plenty.
>The other unopened bags could even act as a stirring source since
>their respective piezo linings could act together in a synergesis of
>stirring.
>I have experimented with Kynar... it will do this.
>
>A PIC controlling it of course.
>
>Maybe I have gone mad?
>Ohh look that mans gone mad!
>
>
>_____________________________
>
>Lance Allen
>Technical Officer
>Uni of Auckland
>Psych Dept
>New Zealand
>_____________________________
>
--- Jim Pennington <spam_OUTpennTakeThisOuTINETNOW.NET> wrote:
> Wait a minute...are you saying that Kynar (usually
> the insulation on wire
> wrap wire) will bend under electrical stimulus???
Well, it would be an interesting possibility but the
piezoelectric Kynar film is usually treated during
manufacture by treating the thin plastic film with
intense electrical fields or by other methods. As far
as I know, wire wrap wire insulation is just plain old
PVDF plastic.
<snip>
Later,
Eric
_____________________________________________________________
Do You Yahoo!?
Bid and sell for free at http://auctions.yahoo.com
Russell McMahon a écrit:
Antenna will be low (possibly as high as
> unity :-)) gain. Carrying and deploying an aerial,
Russell,
I would think that with 10 Watts, a gain antenna is mandatory if you
want to hear it from 400 000 Km.
However, if you think that a low gain aerial would be good enough, it
might actually need no deploying at all. You could use a slot antenna or
a patch antenna.
> Wait a minute...are you saying that Kynar (usually the insulation on wire
> wrap wire) will bend under electrical stimulus??? How does it bend?
> Does it shrink in length? Is it reproducable (i.e. is it a one-time
> effect or will it recover when stimulus is removed)? You say the stimulus
> is low power...what are we talking...+5v at how many milliamps??
> I'd like to reproduce this effect...please describe your experimentation.
>
> Jim
>
Kynar is the "generic name we use", upon reflection Im not so sure
that is absolutely correct . It is a plastic film similar in
appearance and texture to Mylar. The AMP definition is PVFD or piezo
polyvinylidene fluoride. Electrodes are vapour deposited on both sides
of the plastic and the material is piezo electric. A 1 cm by 3cm strip
will produce a dynamic static voltage of around 180volts (in 1 megohm)
when deflected 3cm. Conversely around 200volts across the film will
cause millimetres of dynamic deflection. The material looks like a
capacitor electrically so power drain is tiny. A bi-morph strip of
PVDF will deflect 3-4 centimetres at around 200 volts and an app note
for making a wing flapping butterfly is included in the basic design
kit. I starting using the material because of its sensing capabilities
for Hydrophones. Talk to AMP about it.
And yes..as I said I have been bending it with the afore mentioned
voltages... and driving speakers made of PVDF.
_____________________________
Lance Allen
Technical Officer
Uni of Auckland
Psych Dept
New Zealand
_____________________________
INETNOW.NET> wrote:
