Relay contact ratings.

On 12/12/2011 9:20 AM, mrstarbom@gmail.com wrote:
A motherhood statement which avoids dealing with any unpleasant details. Could you state the problem clearly please. What is your solution?
I probably don't have a solution - I certainly don't have one that could
be accepted.

The problem is the rate at which we can recycle our resources - and this
totally ignores any GW issues.

The problems come about because of these conditions:

10% of the world population consumes 90% of the worlds "active" resources.

The "average" person in the world lives in a one or two room house or
apartment with little or no yard. They probably easy have access to
water and possibly even water in their own house. The water is unlikely
to be safe to drink without further processing. The average house is
likely to have intermittent electrical power for up to 6 hours per day.

The average household is unlikely to have a form of motorised transport
but may have bicycle or animal transport. The average household probably
has to travel up to 24hours to access basic health care.

Think poor rural Mexican and your there.

I don't know about you, but I don't want to live like that. I don't want
my kids to live like that either.

The problems come about because this is happening:

China, India and Indonesia are rapidly industrialising, which is
creating a middle class and a consumer society. They want more, consume
more and are no longer satisfied with less.

Basic supply and demand states quite clearly that this demand pushes up
prices for all basic goods. Increased demand means it will be increasing
difficult and expensive (and eventually impossible) to maintain our
lifestyles while the 90% of the rest of the world is increasingly
becoming modern consumers. There is no way to stop that growth.

The proposed solutions are:

to increase resource extraction and thereby increase the amount of
active resource in the world. This delays catastrophic failure but does
not prevent it. With massive expansion of mining and other resource
extraction might be increased by 2 to 3 times perhaps, even 10 times if
we can mine the depths of the sea, but the current population will
require 80 times that amount if they were to develop to the average
level of consumption in the developed world.

to recycle - or more correctly to recycle faster. Our best efforts to
date have been, collectively, pitiful. Even recycling that is, overall
90% efficient falls short of needs by nearly an order of magnitude.

And all of this is under the most optimistic projection that assumes
that energy is unlimited and consumed with little consequence.

The nettle no one wants to grasp is that the entire world has to control
it's population. We resist this proposition because we already have too
many people and a decreasing population is an invitation to negative
economic growth and negative profits (that case is not inevitable but it
would require careful management to avoid). No one and no business is
prepared for the restrictions required. No government is game to enforce
them on their people.

(The possible exception is China who put out the one child policy with
just this situation in mind, only they were thinking of it in a limited
regional context)

No GW. Just the weight of humanity needing more. That is the end of my
"green" speech. BTW, the quote "we have failed..." is from David Suzuki.

--
We have failed to address the fundamental truth that endless growth is
impossible in a finite world.
 
On Dec 12, 12:47 pm, David Eather <eat...@tpg.com.au> wrote:
On 13/12/2011 2:41 AM, linnix wrote:









On Dec 12, 5:53 am, Sylvia Else<syl...@not.here.invalid>  wrote:
On 12/12/2011 4:20 PM, linnix wrote:

On Dec 11, 5:48 pm, John Fields<jfie...@austininstruments.com>    wrote:
On Sun, 11 Dec 2011 16:20:48 -0800 (PST), linnix

m...@linnix.info-for.us>    wrote:
On Dec 11, 3:09 pm, John Fields<jfie...@austininstruments.com>    wrote:
On Sat, 10 Dec 2011 17:19:52 -0800 (PST), linnix

m...@linnix.info-for.us>    wrote:
On Dec 10, 5:06 pm, John Fields<jfie...@austininstruments.com>    wrote:
You've said the defrost only happens every six hours, but for how long
is the heater energized?

knowing that will allow us to determine the duty cycle of the timer
and cause it to mimic the motor timer.

--
JF

It should be long enough to melt the ice and let the water drain off.
It can easily be programmable in a micro, at least during
development.  Perhaps a 5 to 10 minutes range.

---
Thanks, but I'd prefer some real numbers from Sylvia so that I can
work up a hardware solution for her.

You don't like my numbers?

---
I don't care for conjecture, which is all you're offering.
---

Then go with the number from commerical
defrost timer.
4 minutes to 110 minutes in 2 minutes step.
4 to 12 cycles per day.

http://www.grainger.com/Grainger/PARAGON-Time-InitiatedTime-Terminate....

---
That's USD 184.75, and she's in Oz, so it'd more likely be about USD
250 before she got the part in hand.

Plus, she's got an old fridge and if went belly-up shortly after
spending the money for the defroster she'd probably wind up with a new
fridge and a homeless new defroster.
---

I would go with 2 pots + 2 A2D. adjust and time it with a micro.

---
Yeah, sure you would...

Why not post a schematic and some code showing how you'd propose to
implement your wily scheme, and I'll do the same proposing a strictly
hardware solution?

Game on?

OK, changed my mind, let do digital.

Let start with perhaps 4 buttons. Two to change cycles per day and two
to change durations.  Three bits driving 138 (one of eight) to
indicate cycles (eight cycles should be plenty).  Another three bits
to indicate durations such as 5,7,10,15,20,25,30 minutes.  I doubt we
really want to defrost beyond 30 minutes anyway.  So far, we can do it
with 10 port pins and 16 LEDs.

Just a quick first draft:

char cycle[8] = {1,2,3,4,5,6,7};
char duration[8] = {5,7,10,15,20,25,30};
int c_idx;
int d_idx;

while(1)
{
   if(port(c_up))
    c_idx++;
   if(port(c_dn))
    c_idx--;
   if(port(d_up))
    d_idx++;
   if(port(d_dn))
    d_idx--;

    defrost_on();
    delay(d_idx);
    defrost_off();

    delay_hrs(24/cycle[c_idx]);
}

...

Are c_idx and d_idx in non-volatile RAM? I'd prefer my fridge to
continue working, without intervention, after a power outage.

Depends on the micro.  Some can save to EEPROM.  That's why i though
about pots in the first place.  Pots are non-volatile.  We need an A2D
to read from thermistor anyway, so perhaps using 3 channels A2D.  One
port for the defrost heater and one more for the compressor.  One more
set of decoder/LEDs for temp. settling.  So, to do all the fridge
control:

PIC32MX256DA206 (using 11 digital ports and 3 analog ports)
Actually, PIC32MX575L256, 11 digital and 4 analog ports. Just
checking if anyone is awake here.

100K Pots (x3)
74XXX138 (x3)
LED (x24)
Thermistor
240V/5A AC relay (x2)
etc.

Seriously, PICAXE 08M2 - 3 x 10 bit digital ports, configures and reads
as 8 or ten bits with with a single "readadc" or "readadc10" command
(IIRC) and 256 bytes eeprom reads and writes with simple single line
instructions. PICAXE is the simplest and fastest solution to any one off
that needs a little smarts and not too much speed bar none. If you need
lots of LEDs one of the bigger PICAXE chips will do.

I have programmed (and still do) PIC's in assembler (very badly - I
still do that very badly too), Microchip C, Swordfish Basic, and
PICBASIC Pro. For speed, cost effectiveness and ease of producing a
one-off PICAXE easily cleans the floor with all of them.
I can do a one-off PIC32 faster than PICAXE. I don't like doing
decimal bit maps in BASIC.
 
Poverty is not caused by a shortage of resources but by a shortage of good government, by greed, by corruption, in short by evil. If you listen uncritically to David Suzuki you will end up as ignorant as he is. The Chinese developed an oversupply of men - last I heard 7 million more than women and now an oversupply of old people. Brilliant piece of cruelty on their part.. Just think about the numbers of murders they have forced on people. His ideas are so recycled (proved wrong over and over) and stem from a belief that people can make themselves good.
 
On Dec 12, 5:20 am, linnix <m...@linnix.info-for.us> wrote:
On Dec 11, 5:48 pm, John Fields <jfie...@austininstruments.com> wrote:



On Sun, 11 Dec 2011 16:20:48 -0800 (PST), linnix

m...@linnix.info-for.us> wrote:
On Dec 11, 3:09 pm, John Fields <jfie...@austininstruments.com> wrote:
On Sat, 10 Dec 2011 17:19:52 -0800 (PST), linnix

m...@linnix.info-for.us> wrote:
On Dec 10, 5:06 pm, John Fields <jfie...@austininstruments.com> wrote:
You've said the defrost only happens every six hours, but for how long
is the heater energized?

knowing that will allow us to determine the duty cycle of the timer
and cause it to mimic the motor timer.

--
JF

It should be long enough to melt the ice and let the water drain off.
It can easily be programmable in a micro, at least during
development.  Perhaps a 5 to 10 minutes range.

---
Thanks, but I'd prefer some real numbers from Sylvia so that I can
work up a hardware solution for her.

You don't like my numbers?

---
I don't care for conjecture, which is all you're offering.
---

Then go with the number from commerical
defrost timer.
4 minutes to 110 minutes in 2 minutes step.
4 to 12 cycles per day.

http://www.grainger.com/Grainger/PARAGON-Time-InitiatedTime-Terminate....

---
That's USD 184.75, and she's in Oz, so it'd more likely be about USD
250 before she got the part in hand.

Plus, she's got an old fridge and if went belly-up shortly after
spending the money for the defroster she'd probably wind up with a new
fridge and a homeless new defroster.
---

I would go with 2 pots + 2 A2D. adjust and time it with a micro.

---
Yeah, sure you would...

Why not post a schematic and some code showing how you'd propose to
implement your wily scheme, and I'll do the same proposing a strictly
hardware solution?

Game on?

OK, changed my mind, let do digital.

Let start with perhaps 4 buttons. Two to change cycles per day and two
to change durations.  Three bits driving 138 (one of eight) to
indicate cycles (eight cycles should be plenty).  Another three bits
to indicate durations such as 5,7,10,15,20,25,30 minutes.  I doubt we
really want to defrost beyond 30 minutes anyway.  So far, we can do it
with 10 port pins and 16 LEDs.

Just a quick first draft:

char cycle[8] = {1,2,3,4,5,6,7};
char duration[8] = {5,7,10,15,20,25,30};
int c_idx;
int d_idx;

while(1)
{
 if(port(c_up))
  c_idx++;
 if(port(c_dn))
  c_idx--;
 if(port(d_up))
  d_idx++;
 if(port(d_dn))
  d_idx--;

  defrost_on();
  delay(d_idx);
  defrost_off();

  delay_hrs(24/cycle[c_idx]);

}

...
Its a better idea to stop defrost cycle when the exchanger temp rises
above freezing. Otherwie you're wasting energy, and at some point the
machine will likely ice up.


NT
 
On Dec 8, 7:36 pm, Trevor Wilson <tre...@SPAMBLOCKrageaudio.com.au>
wrote:

The US lacks a cohesive socialised medical system. As a
consequence, some 50-odd million Americans have extremely poor access to
good medical services. Additionally, some 60% of personal bankruptcies
in the US are due to medical bills.
<OT>

FWIW, those are oft-cited misconceptions. Media drones repeat them
without understanding their basis.

The number is ~32 million, and these are people who do not have
medical insurance. That is not the same as "extremely poor access" to
care. Numerically, some 10-12 million of that figure are illegal
aliens, and most of the remainder are young people who voluntarily
choose not to buy it. Access is generally good to excellent.

60-odd % is the proportion of people who go bankrupt who, among their
other bills, also owe money to their doctors. The number whose
medical costs *caused* their bankruptcy is a small fraction.

Last, everyone can get care. There are countless medical programs for
the poor.

I personally have an acquaintance getting the full royal treatment,
for cancer, for nothing. She's better than most at working the
system, but it's there for people who need it, and seek it.

</OT>

--
Cheers,
James Arthur
 
On Dec 12, 2:23 pm, NT <meow2...@care2.com> wrote:
On Dec 12, 5:20 am, linnix <m...@linnix.info-for.us> wrote:









On Dec 11, 5:48 pm, John Fields <jfie...@austininstruments.com> wrote:

On Sun, 11 Dec 2011 16:20:48 -0800 (PST), linnix

m...@linnix.info-for.us> wrote:
On Dec 11, 3:09 pm, John Fields <jfie...@austininstruments.com> wrote:
On Sat, 10 Dec 2011 17:19:52 -0800 (PST), linnix

m...@linnix.info-for.us> wrote:
On Dec 10, 5:06 pm, John Fields <jfie...@austininstruments.com> wrote:
You've said the defrost only happens every six hours, but for how long
is the heater energized?

knowing that will allow us to determine the duty cycle of the timer
and cause it to mimic the motor timer.

--
JF

It should be long enough to melt the ice and let the water drain off.
It can easily be programmable in a micro, at least during
development.  Perhaps a 5 to 10 minutes range.

---
Thanks, but I'd prefer some real numbers from Sylvia so that I can
work up a hardware solution for her.

You don't like my numbers?

---
I don't care for conjecture, which is all you're offering.
---

Then go with the number from commerical
defrost timer.
4 minutes to 110 minutes in 2 minutes step.
4 to 12 cycles per day.

http://www.grainger.com/Grainger/PARAGON-Time-InitiatedTime-Terminate...

---
That's USD 184.75, and she's in Oz, so it'd more likely be about USD
250 before she got the part in hand.

Plus, she's got an old fridge and if went belly-up shortly after
spending the money for the defroster she'd probably wind up with a new
fridge and a homeless new defroster.
---

I would go with 2 pots + 2 A2D. adjust and time it with a micro.

---
Yeah, sure you would...

Why not post a schematic and some code showing how you'd propose to
implement your wily scheme, and I'll do the same proposing a strictly
hardware solution?

Game on?

OK, changed my mind, let do digital.

Let start with perhaps 4 buttons. Two to change cycles per day and two
to change durations.  Three bits driving 138 (one of eight) to
indicate cycles (eight cycles should be plenty).  Another three bits
to indicate durations such as 5,7,10,15,20,25,30 minutes.  I doubt we
really want to defrost beyond 30 minutes anyway.  So far, we can do it
with 10 port pins and 16 LEDs.

Just a quick first draft:

char cycle[8] = {1,2,3,4,5,6,7};
char duration[8] = {5,7,10,15,20,25,30};
int c_idx;
int d_idx;

while(1)
{
 if(port(c_up))
  c_idx++;
 if(port(c_dn))
  c_idx--;
 if(port(d_up))
  d_idx++;
 if(port(d_dn))
  d_idx--;

  defrost_on();
  delay(d_idx);
  defrost_off();

  delay_hrs(24/cycle[c_idx]);

}

...

Its a better idea to stop defrost cycle when the exchanger temp rises
above freezing. Otherwie you're wasting energy, and at some point the
machine will likely ice up.
Yes, we will need one or more thermistors or thermocouples to monitor
the temperature.
 
On 13/12/2011 9:23 AM, NT wrote:
On Dec 12, 5:20 am, linnix<m...@linnix.info-for.us> wrote:
On Dec 11, 5:48 pm, John Fields<jfie...@austininstruments.com> wrote:



On Sun, 11 Dec 2011 16:20:48 -0800 (PST), linnix

m...@linnix.info-for.us> wrote:
On Dec 11, 3:09 pm, John Fields<jfie...@austininstruments.com> wrote:
On Sat, 10 Dec 2011 17:19:52 -0800 (PST), linnix

m...@linnix.info-for.us> wrote:
On Dec 10, 5:06 pm, John Fields<jfie...@austininstruments.com> wrote:
You've said the defrost only happens every six hours, but for how long
is the heater energized?

knowing that will allow us to determine the duty cycle of the timer
and cause it to mimic the motor timer.

--
JF

It should be long enough to melt the ice and let the water drain off.
It can easily be programmable in a micro, at least during
development. Perhaps a 5 to 10 minutes range.

---
Thanks, but I'd prefer some real numbers from Sylvia so that I can
work up a hardware solution for her.

You don't like my numbers?

---
I don't care for conjecture, which is all you're offering.
---

Then go with the number from commerical
defrost timer.
4 minutes to 110 minutes in 2 minutes step.
4 to 12 cycles per day.

http://www.grainger.com/Grainger/PARAGON-Time-InitiatedTime-Terminate...

---
That's USD 184.75, and she's in Oz, so it'd more likely be about USD
250 before she got the part in hand.

Plus, she's got an old fridge and if went belly-up shortly after
spending the money for the defroster she'd probably wind up with a new
fridge and a homeless new defroster.
---

I would go with 2 pots + 2 A2D. adjust and time it with a micro.

---
Yeah, sure you would...

Why not post a schematic and some code showing how you'd propose to
implement your wily scheme, and I'll do the same proposing a strictly
hardware solution?

Game on?

OK, changed my mind, let do digital.

Let start with perhaps 4 buttons. Two to change cycles per day and two
to change durations. Three bits driving 138 (one of eight) to
indicate cycles (eight cycles should be plenty). Another three bits
to indicate durations such as 5,7,10,15,20,25,30 minutes. I doubt we
really want to defrost beyond 30 minutes anyway. So far, we can do it
with 10 port pins and 16 LEDs.

Just a quick first draft:

char cycle[8] = {1,2,3,4,5,6,7};
char duration[8] = {5,7,10,15,20,25,30};
int c_idx;
int d_idx;

while(1)
{
if(port(c_up))
c_idx++;
if(port(c_dn))
c_idx--;
if(port(d_up))
d_idx++;
if(port(d_dn))
d_idx--;

defrost_on();
delay(d_idx);
defrost_off();

delay_hrs(24/cycle[c_idx]);

}

...

Its a better idea to stop defrost cycle when the exchanger temp rises
above freezing. Otherwie you're wasting energy, and at some point the
machine will likely ice up.


NT
The 'standard' self-defrost implementation has an additional thermostat
on the cooling element, which trips open when the element reaches some
predetermined temperature (11C on mine), and closes again at some lower
temperature (0C on mine).

11C seems rather high, but I suppose it's intended to ensure that the
entire element has defrosted, not just the part near the thermostat. It
also means the thermostat need not be that accurate.

Switching the cooling back on immediately after the thermostat trips off
seems attractive, to avoid defrosting the stuff in the freezer, but I
have some misgivings about the impact on the compressor of starting when
the element is that warm.

It's not clear to me why the machine would ice up if the defrost cycle
is left running too long.

Sylvia.
 
On 13/12/2011 7:26 AM, Michael A. Terrell wrote:
Sylvia Else wrote:

On 12/12/2011 5:58 PM, Michael A. Terrell wrote:
?
? Sylvia Else wrote:
??
?? On 12/12/2011 12:57 PM, John Fields wrote:
??? On Mon, 12 Dec 2011 12:30:26 +1100, Sylvia Else
??? ?sylvia@not.here.invalid? wrote:
???
???? On 11/12/2011 5:00 PM, Michael A. Terrell wrote:
?????
????? Sylvia Else wrote:
??????
?????? On 11/12/2011 3:46 AM, Michael A. Terrell wrote:
???????
??????? Sylvia Else wrote:
?????????
????????? There are aftermarket universals better than the OEM part
????????? http://compare.ebay.com/like/290638915750?var=lv?ltyp=AllFixedPriceItemTypes?var=sbar
????????
???????? Though not 240V versions as far as I can see. Pity.
???????
???????
??????? Can't you find a cheap 240 to 120 VAC transformer?
???????
??????
?????? I could. Using it wouldn't be so straight forward. The timer has a
?????? single pin for input, which is both the source of power for the clock,
?????? and for running either the compressor and heater.
?????
?????
????? There is no neutral connection to the timer?
?????
?????
???? OK, I suppose that would work, though the thing would still be switching
???? voltage which is double its design rating.
????
???? Sylvia.
???
??? Huh???
???
??
?? Since I'm in Australia, both the defrost heater and the compressor are
?? rated at 240V. Anything that switches them on and off has to switch 240V.
?
?
? It would have to switch half the current it would on 120 VAC, and the
? relays are the same for either line volktage.
?
?

You've taken one apart?



I've taken apart a lot of things and I've never seen a power relay
with 120 volt rated contacts. Do whatever you want, I'm done with this
thread.
Well, I obviously can't say what you've see, but here's relay with 120V
rated contacts.

http://australia.rs-online.com/web/p/electromechanical-relays/4936458/

Sylvia.
 
On Tue, 13 Dec 2011 06:51:59 +1000, David Eather <eather@tpg.com.au>
wrote:

On 12/12/2011 8:59 AM, John Fields wrote:
On Mon, 12 Dec 2011 07:50:45 +1000, David Eather<eather@tpg.com.au
wrote:

On 11/12/2011 10:09 AM, John Fields wrote:
On Sun, 11 Dec 2011 07:30:25 +1000, David Eather<eather@tpg.com.au
wrote:

On 10/12/2011 10:32 AM, John Fields wrote:
On Sat, 10 Dec 2011 09:14:27 +1000, David Eather<eather@tpg.com.au
wrote:

We have failed to address the fundamental truth that endless growth is
impossible in a finite world.

---
Not true; consider Moore's law.


Consider that Moore's Law is not a law.

---
OK, Moore's conjecture then, if that pleases you.

The point is that we _have_ addressed the fundamental truth that
endless growth is impossible in a finite world by stalling the
inevitable using miniaturization.


You mean we have found a way to avoid having to do anything unpleasant
to ourselves by foisting the problem on a latter generation. And you
think this is a "solution"?

---
Certainly you must have misunderstood.

In the context of Moore's Law:

http://en.wikipedia.org/wiki/File:Transistor_Count_and_Moore%27s_Law_-_2011.svg

we _have_ addressed the fundamental truth that endless growth is
impossible in a finite world by diminishing the size of transistors in
order to pack more and more of them into smaller areas as time goes
by.

This allows us to build more powerful machines which, rather than
foisting out problems on future generations, will help us solve some
of ours, and theirs as well.

Your suggestion that we should make life more unpleasant for ourselves
by not taking Moore's Law into account and building computers out of,
say, 2N2222's is puzzling


"Moore's Law" fails when you get to one atom sized conductors (in
practical terms we can expect it to fail before then)

"Moor's law" is about one, specific and small situation. By appealing to
"Moore's Law" as a general solution you are burying your head in the sand.
---
By admitting - ergo addressing the fact - that there _is_ a limit to
the application of Moore's Law, your .sig: "We have failed to address
the fundamental truth that endless growth is impossible in a finite
world." is rendered invalid since you, at least, have not failed to
recognize that endless growth is impossible in a finite world.

--
JF
 
On Dec 12, 4:36 pm, David Eather <eat...@tpg.com.au> wrote:
On 12/12/2011 9:20 AM, mrstar...@gmail.com wrote:

A motherhood statement which avoids dealing with any unpleasant details..  Could you state the problem clearly please.  What is your solution?

I probably don't have a solution - I certainly don't have one that could
be accepted.

The problem is the rate at which we can recycle our resources - and this
totally ignores any GW issues.

The problems come about because of these conditions:

10% of the world population consumes 90% of the worlds "active" resources..

The "average" person in the world lives in a one or two room house or
apartment with little or no yard. They probably easy have access to
water and possibly even water in their own house. The water is unlikely
to be safe to drink without further processing. The average house is
likely to have intermittent electrical power for up to 6 hours per day.

The average household is unlikely to have a form of motorised transport
but may have bicycle or animal transport. The average household probably
has to travel up to 24hours to access basic health care.

Think poor rural Mexican and your there.

I don't know about you, but I don't want to live like that. I don't want
my kids to live like that either.

The problems come about because this is happening:

China, India and Indonesia are rapidly industrialising, which is
creating a middle class and a consumer society. They want more, consume
more and are no longer satisfied with less.

Basic supply and demand states quite clearly that this demand pushes up
prices for all basic goods. Increased demand means it will be increasing
difficult and expensive (and eventually impossible) to maintain our
lifestyles while the 90% of the rest of the world is increasingly
becoming modern consumers. There is no way to stop that growth.

The proposed solutions are:

to increase resource extraction and thereby increase the amount of
active resource in the world. This delays catastrophic failure but does
not prevent it. With massive expansion of mining and other resource
extraction might be increased by 2 to 3 times perhaps, even 10 times if
we can mine the depths of the sea, but the current population will
require 80 times that amount if they were to develop to the average
level of consumption in the developed world.

to recycle - or more correctly to recycle faster. Our best efforts to
date have been, collectively, pitiful. Even recycling that is, overall
90% efficient falls short of needs by nearly an order of magnitude.

And all of this is under the most optimistic projection that assumes
that energy is unlimited and consumed with little consequence.

The nettle no one wants to grasp is that the entire world has to control
it's population. We resist this proposition because we already have too
many people and a decreasing population is an invitation to negative
economic growth and negative profits (that case is not inevitable but it
would require careful management to avoid). No one and no business is
prepared for the restrictions required. No government is game to enforce
them on their people.

(The possible exception is China who put out the one child policy with
just this situation in mind, only they were thinking of it in a limited
regional context)

No GW. Just the weight of humanity needing more. That is the end of my
"green" speech. BTW, the quote "we have failed..." is from David Suzuki.

--
We have failed to address the fundamental truth that endless growth is
impossible in a finite world.
Wow, I mostly agree, We vote with 'our dollars' every day.
If a lot of us ask for products that cost more,
but last longer, then someone will make them.

That's the theory anyway.

Till then, buy old stuff and keep it running.

George H.
 
Put another way, the world is finite. Panic!
'10% of the world's population consumes 90% of the world's resources' is not really newsworthy. There have always been really rich people and really poor people, there just weren't so many of them.
What are "active" resources?
What makes you so sure there is no way to stop that growth? After all, the world is finite. :) It is very likely that lifespans will begin to decrease due to lifestyle and 'modern' toxins, and at any time thousands could be wiped out very rapidly by some new plague.
Apparently, the Chinese are working on another 'solution'. Having tried building without reinforcing, they are now stretching the steel used in reinforcing. ;)
BTW - how many children do you have? They're more likely to suffer as a result of doing something stupid than because the world is finite. Your description sounds quite a bit like rural Australia, for some people.
 
Sylvia Else wrote:
On 13/12/2011 7:26 AM, Michael A. Terrell wrote:


Sylvia Else wrote:


On 12/12/2011 5:58 PM, Michael A. Terrell wrote:
?
? Sylvia Else wrote:
??
?? On 12/12/2011 12:57 PM, John Fields wrote:
??? On Mon, 12 Dec 2011 12:30:26 +1100, Sylvia Else
??? ?sylvia@not.here.invalid? wrote:
???
???? On 11/12/2011 5:00 PM, Michael A. Terrell wrote:
?????
????? Sylvia Else wrote:
??????
?????? On 11/12/2011 3:46 AM, Michael A. Terrell wrote:
???????
??????? Sylvia Else wrote:
?????????
????????? There are aftermarket universals better than the OEM part
?????????
http://compare.ebay.com/like/290638915750?var=lv?ltyp=AllFixedPriceItemTypes?var=sbar

????????
???????? Though not 240V versions as far as I can see. Pity.
???????
???????
??????? Can't you find a cheap 240 to 120 VAC transformer?
???????
??????
?????? I could. Using it wouldn't be so straight forward. The timer
has a
?????? single pin for input, which is both the source of power for
the clock,
?????? and for running either the compressor and heater.
?????
?????
????? There is no neutral connection to the timer?
?????
?????
???? OK, I suppose that would work, though the thing would still be
switching
???? voltage which is double its design rating.
????
???? Sylvia.
???
??? Huh???
???
??
?? Since I'm in Australia, both the defrost heater and the compressor
are
?? rated at 240V. Anything that switches them on and off has to
switch 240V.
?
?
? It would have to switch half the current it would on 120 VAC,
and the
? relays are the same for either line volktage.
?
?

You've taken one apart?




I've taken apart a lot of things and I've never seen a power relay
with 120 volt rated contacts. Do whatever you want, I'm done with this
thread.



Well, I obviously can't say what you've see, but here's relay with 120V
rated contacts.

http://australia.rs-online.com/web/p/electromechanical-relays/4936458/

Sylvia.
Mike said _power_ relay. The one in the url you posted is a
signal relay.

Ed
 
On Dec 13, 10:40 am, Sylvia Else <syl...@not.here.invalid> wrote:
On 13/12/2011 9:23 AM, NT wrote:



On Dec 12, 5:20 am, linnix<m...@linnix.info-for.us>  wrote:
On Dec 11, 5:48 pm, John Fields<jfie...@austininstruments.com>  wrote:

On Sun, 11 Dec 2011 16:20:48 -0800 (PST), linnix

m...@linnix.info-for.us>  wrote:
On Dec 11, 3:09 pm, John Fields<jfie...@austininstruments.com>  wrote:
On Sat, 10 Dec 2011 17:19:52 -0800 (PST), linnix

m...@linnix.info-for.us>  wrote:
On Dec 10, 5:06 pm, John Fields<jfie...@austininstruments.com>  wrote:
You've said the defrost only happens every six hours, but for how long
is the heater energized?

knowing that will allow us to determine the duty cycle of the timer
and cause it to mimic the motor timer.

--
JF

It should be long enough to melt the ice and let the water drain off.
It can easily be programmable in a micro, at least during
development.  Perhaps a 5 to 10 minutes range.

---
Thanks, but I'd prefer some real numbers from Sylvia so that I can
work up a hardware solution for her.

You don't like my numbers?

---
I don't care for conjecture, which is all you're offering.
---

Then go with the number from commerical
defrost timer.
4 minutes to 110 minutes in 2 minutes step.
4 to 12 cycles per day.

http://www.grainger.com/Grainger/PARAGON-Time-InitiatedTime-Terminate....

---
That's USD 184.75, and she's in Oz, so it'd more likely be about USD
250 before she got the part in hand.

Plus, she's got an old fridge and if went belly-up shortly after
spending the money for the defroster she'd probably wind up with a new
fridge and a homeless new defroster.
---

I would go with 2 pots + 2 A2D. adjust and time it with a micro.

---
Yeah, sure you would...

Why not post a schematic and some code showing how you'd propose to
implement your wily scheme, and I'll do the same proposing a strictly
hardware solution?

Game on?

OK, changed my mind, let do digital.

Let start with perhaps 4 buttons. Two to change cycles per day and two
to change durations.  Three bits driving 138 (one of eight) to
indicate cycles (eight cycles should be plenty).  Another three bits
to indicate durations such as 5,7,10,15,20,25,30 minutes.  I doubt we
really want to defrost beyond 30 minutes anyway.  So far, we can do it
with 10 port pins and 16 LEDs.

Just a quick first draft:

char cycle[8] = {1,2,3,4,5,6,7};
char duration[8] = {5,7,10,15,20,25,30};
int c_idx;
int d_idx;

while(1)
{
  if(port(c_up))
   c_idx++;
  if(port(c_dn))
   c_idx--;
  if(port(d_up))
   d_idx++;
  if(port(d_dn))
   d_idx--;

   defrost_on();
   delay(d_idx);
   defrost_off();

   delay_hrs(24/cycle[c_idx]);

}

...

Its a better idea to stop defrost cycle when the exchanger temp rises
above freezing. Otherwie you're wasting energy, and at some point the
machine will likely ice up.

NT

The 'standard' self-defrost implementation has an additional thermostat
on the cooling element, which trips open when the element reaches some
predetermined temperature (11C on mine), and closes again at some lower
temperature (0C on mine).

11C seems rather high, but I suppose it's intended to ensure that the
entire element has defrosted, not just the part near the thermostat. It
also means the thermostat need not be that accurate.

Switching the cooling back on immediately after the thermostat trips off
seems attractive, to avoid defrosting the stuff in the freezer, but I
have some misgivings about the impact on the compressor of starting when
the element is that warm.

It's not clear to me why the machine would ice up if the defrost cycle
is left running too long.

Sylvia.

You could design a defrost system like was on the New Inventors last
year.
IIRC a resistive strip was placed in the freezer, a known voltage
passed through it periodically
and the resistance of it measured (heat causes resistance to rise, and
the more frost/ice formed on the strip
the longer it took to heat up and resistance to rise) and turn on the
defrost system only when
sufficient ice was detected.
 
On Dec 11, 9:16 am, linnix <m...@linnix.info-for.us> wrote:
On Dec 10, 2:39 pm, kreed <kenreed1...@gmail.com> wrote:



On Dec 10, 9:00 pm, Sylvia Else <syl...@not.here.invalid> wrote:

On 10/12/2011 9:33 PM, kreed wrote:

On Dec 10, 8:28 pm, Sylvia Else<syl...@not.here.invalid>  wrote:
On 10/12/2011 10:14 AM, David Eather wrote:

On 9/12/2011 10:56 AM, Sylvia Else wrote:
On 9/12/2011 4:23 AM, linnix wrote:
On Dec 8, 9:01 am, Fred Bloggs<bloggs.fredbloggs.f...@gmail.com
wrote:
On Dec 8, 1:50 am, Sylvia Else<syl...@not.here.invalid>  wrote:

The defrost timer in my fridge is failing, and given the cost of a
'genuine' replacement part, I was pondering the option of making
electronic timer driving an electromechanical relay.

It probably won't happen, but when I was looking at relay specs, I
found
that their ratings are usually specified as a highish reactive power,
and a much lower real power.

http://australia.rs-online.com/web/p/electromechanical-relays/1279550/

is typical, specifying in this case 300 W / 2500 VA.

I find this difficult to fathom. Imagine a purely inductive 2500VA
load.
So no real power being switched, but it would arc like crazy. What
am I
missing here?

Sylvia.

There are aftermarket universals better than the OEM
parthttp://compare.ebay.com/like/290638915750?var=lv<yp=AllFixedPriceIt...

There are plenty of relays you can salvage out of garage opener (12V),
microwave (12V) or furnace (24V). Add a micro or 555 for less than $5
and you are done. I am doing one for my furnace timer.

Not sure about getting a 555 to run at 1 cycle per six hours.

A PIC would no doubt do the job easily, but then I'd have to invest in
hardware to program it.

Sylvia.

Sylvia,

Try a PICAXE 08M2 - it costs $2.50 in one off's and programs in BASIC.
Software and examples are free fromwww.picaxe.co.uk
It is not uncommon for people totally new to the PICAXE have had them
running programs within 30 minutes of getting their first chip.

The only stuff you need to program one is a serial port (RS232 or TTL
level) and a resistor.

Interesting. Thanks.

I'm tempted to combine the timer with the thermostat, a replacement for
which I've been cursin..., er, I mean testing, today. (Sod's law
subsection 3.1 - a fridge must always enter defrost mode while a person
is attempting to adjust the upper and lower settings of a thermostat.)

Of course, I could just buy a new fridge.

Sylvia.

Depends on how old, and how good the current one is other than this
current problem.  New ones might be even worse :)

It would have to be at least ten, and it's been running all that time..

The big question, of course, is how much longer the compressor will
last, since it's probably not going to possible to source a replacement,
even if it would otherwise be economically worthwhile.

BTW, the wires are attached to the (mains-voltage) lamp socket by way of
spring clips. Seems a bit iffy to me.

Sylvia.

I remember a few years back there was one of these educational
programs on how things work, in particular household appliances.  They
actually went to a dump site where were were dozens of junked fridges,
and connected each one to power.  Almost all still cooled, but had
been dumped due to rust, broken shelves, seals etc or other similar
damage.  They said that the compressors were extremely reliable.

OK, i am going dumper diving.

...
As for that electronic aftermarket timer from Ebay that is 120v - if
you get one and open it up, you might find that it has either a
switchmode power supply or a series capacitor type supply.  You can
modify these fairly easily to run from 240v, or make up a small power
supply that you can mount in the back of the fridge.  For something
like this a linear power supply might be best, as linear ones are very
reliable.

Actually, a good source of relays are garage openers.  I have a spare
board with 3 240V/5A w 24V/5A coil.  I guess it needs open/close/on.



I have worked on a couple of newer Australian made ones here and now
they have no relays at all in them. Other brands
might have, or older models that are being replaced.
 
On Dec 13, 10:44 am, Sylvia Else <syl...@not.here.invalid> wrote:
On 13/12/2011 7:26 AM, Michael A. Terrell wrote:





Sylvia Else wrote:

On 12/12/2011 5:58 PM, Michael A. Terrell wrote:
?
? Sylvia Else wrote:
??
?? On 12/12/2011 12:57 PM, John Fields wrote:
??? On Mon, 12 Dec 2011 12:30:26 +1100, Sylvia Else
??? ?syl...@not.here.invalid?   wrote:
???
???? On 11/12/2011 5:00 PM, Michael A. Terrell wrote:
?????
????? Sylvia Else wrote:
??????
?????? On 11/12/2011 3:46 AM, Michael A. Terrell wrote:
???????
??????? Sylvia Else wrote:
?????????
????????? There are aftermarket universals better than the OEM part
?????????http://compare.ebay.com/like/290638915750?var=lv?ltyp=AllFixedPriceIt...
????????
???????? Though not 240V versions as far as I can see. Pity.
???????
???????
???????        Can't you find a cheap 240 to 120 VAC transformer?
???????
??????
?????? I could. Using it wouldn't be so straight forward. The timer has a
?????? single pin for input, which is both the source of power for the clock,
?????? and for running either the compressor and heater.
?????
?????
?????       There is no neutral connection to the timer?
?????
?????
???? OK, I suppose that would work, though the thing would still be switching
???? voltage which is double its design rating.
????
???? Sylvia.
???
??? Huh???
???
??
?? Since I'm in Australia, both the defrost heater and the compressor are
?? rated at 240V. Anything that switches them on and off has to switch 240V.
?
?
?     It would have to switch half the current it would on 120 VAC, and the
? relays are the same for either line volktage.
?
?

You've taken one apart?

    I've taken apart a lot of things and I've never seen a power relay
with 120 volt rated contacts. Do whatever you want, I'm done with this
thread.

Well, I obviously can't say what you've see, but here's relay with 120V
rated contacts.

http://australia.rs-online.com/web/p/electromechanical-relays/4936458/

Sylvia.

I have checked a few from my junk box, any that are intended to switch
mains power and not signal
circuits have a 240v rating. Many were out of junked
US made equipment and made in Japan, Mexico or Taiwan.

As they are for the world market, I would think that most would be
rated 240v.

One Japan made one that is UL rated has an inductive rating of 5a
240VAC and 0.5a at 120VDC for inductive loads.

5A 120V and 32v for resistive loads.


The contact clearance is about 1mm.
 
kreed wrote:
On Dec 11, 9:16 am, linnix<m...@linnix.info-for.us> wrote:
On Dec 10, 2:39 pm, kreed<kenreed1...@gmail.com> wrote:



On Dec 10, 9:00 pm, Sylvia Else<syl...@not.here.invalid> wrote:

On 10/12/2011 9:33 PM, kreed wrote:

On Dec 10, 8:28 pm, Sylvia Else<syl...@not.here.invalid> wrote:
On 10/12/2011 10:14 AM, David Eather wrote:

On 9/12/2011 10:56 AM, Sylvia Else wrote:
On 9/12/2011 4:23 AM, linnix wrote:
On Dec 8, 9:01 am, Fred Bloggs<bloggs.fredbloggs.f...@gmail.com
wrote:
On Dec 8, 1:50 am, Sylvia Else<syl...@not.here.invalid> wrote:

The defrost timer in my fridge is failing, and given the cost of a
'genuine' replacement part, I was pondering the option of making
electronic timer driving an electromechanical relay.

It probably won't happen, but when I was looking at relay specs, I
found
that their ratings are usually specified as a highish reactive power,
and a much lower real power.

http://australia.rs-online.com/web/p/electromechanical-relays/1279550/

is typical, specifying in this case 300 W / 2500 VA.

I find this difficult to fathom. Imagine a purely inductive 2500VA
load.
So no real power being switched, but it would arc like crazy. What
am I
missing here?

Sylvia.

There are aftermarket universals better than the OEM
parthttp://compare.ebay.com/like/290638915750?var=lv<yp=AllFixedPriceIt...

There are plenty of relays you can salvage out of garage opener (12V),
microwave (12V) or furnace (24V). Add a micro or 555 for less than $5
and you are done. I am doing one for my furnace timer.

Not sure about getting a 555 to run at 1 cycle per six hours.

A PIC would no doubt do the job easily, but then I'd have to invest in
hardware to program it.

Sylvia.

Sylvia,

Try a PICAXE 08M2 - it costs $2.50 in one off's and programs in BASIC.
Software and examples are free fromwww.picaxe.co.uk
It is not uncommon for people totally new to the PICAXE have had them
running programs within 30 minutes of getting their first chip.

The only stuff you need to program one is a serial port (RS232 or TTL
level) and a resistor.

Interesting. Thanks.

I'm tempted to combine the timer with the thermostat, a replacement for
which I've been cursin..., er, I mean testing, today. (Sod's law
subsection 3.1 - a fridge must always enter defrost mode while a person
is attempting to adjust the upper and lower settings of a thermostat.)

Of course, I could just buy a new fridge.

Sylvia.

Depends on how old, and how good the current one is other than this
current problem. New ones might be even worse :)

It would have to be at least ten, and it's been running all that time.

The big question, of course, is how much longer the compressor will
last, since it's probably not going to possible to source a replacement,
even if it would otherwise be economically worthwhile.

BTW, the wires are attached to the (mains-voltage) lamp socket by way of
spring clips. Seems a bit iffy to me.

Sylvia.

I remember a few years back there was one of these educational
programs on how things work, in particular household appliances. They
actually went to a dump site where were were dozens of junked fridges,
and connected each one to power. Almost all still cooled, but had
been dumped due to rust, broken shelves, seals etc or other similar
damage. They said that the compressors were extremely reliable.

OK, i am going dumper diving.

...
As for that electronic aftermarket timer from Ebay that is 120v - if
you get one and open it up, you might find that it has either a
switchmode power supply or a series capacitor type supply. You can
modify these fairly easily to run from 240v, or make up a small power
supply that you can mount in the back of the fridge. For something
like this a linear power supply might be best, as linear ones are very
reliable.

Actually, a good source of relays are garage openers. I have a spare
board with 3 240V/5A w 24V/5A coil. I guess it needs open/close/on.




I have worked on a couple of newer Australian made ones here and now
they have no relays at all in them. Other brands
might have, or older models that are being replaced.

A lot of the modern ones use butane as a refrigerant so may be they do
not want open contacts in the very remote case of leaks
 
Population projections in 000s(The World Bank)

China 2010 1 338 300
2050 1 273 054

India 2010 1 170 938
2050 1 609 787

By 2050 I expect I'll be past caring.
If you Google "population growth rate" for each country,you'll find a nice graph showing the rate is declining. We really do not need to worry about endless growth, except around the waistline.
 
On 13/12/2011 1:22 PM, mrstarbom@gmail.com wrote:
Put another way, the world is finite. Panic!
'10% of the world's population consumes 90% of the world's resources' is not really newsworthy. There have always been really rich people and really poor people, there just weren't so many of them.
In developing countries the "really poor" are on there way to middle
class and a consumer society. A trivial example - Pakistan and India
both export rice even though there are starving people in their own
countries. The owners of the resource sell it overseas because they can
get more profit for it. The more the starving can pay for that rice the
higher the price will be in the developed world (simple supply and
demand).

What are "active" resources?
Simple concept - think usable. Some stuff is usable only once. Other
stuff is easily recyclable to be used many times.

What makes you so sure there is no way to stop that growth?
No one has yet. I said there might be a solution but that it is probably
unacceptable.

After all, the world is finite. :) It is very likely that lifespans will
begin to decrease due to lifestyle and 'modern' toxins,

Rubbish. Life span may go down a few years from obesity etc but life
expectancy has (in Oz for example) increased by more than 10 years since
1975. It is going to take a whole lot of fat to reverse that - and ill
health also consumes more resources.

and at any time thousands could be wiped out very rapidly by some new
plague.

20 million have been wiped out by aids - did you notice the population
is still growing - its a drop in the bucket.

Apparently, the Chinese are working on another 'solution'. Having tried building without reinforcing, they are now stretching the steel used in reinforcing. ;)
BTW - how many children do you have?
MYOB

They're more likely to suffer as a result of doing something stupid than
because the world is finite.

Currently true. May not always be true.

Your description sounds quite a bit like rural Australia, for some people.

Unfortunately, that is a difficult problem.


--
We have failed to address the fundamental truth that endless growth is
impossible in a finite world.
 
On Dec 13, 5:12 pm, F Murtz <hagg...@hotmail.com> wrote:
kreed wrote:
On Dec 11, 9:16 am, linnix<m...@linnix.info-for.us>  wrote:
On Dec 10, 2:39 pm, kreed<kenreed1...@gmail.com>  wrote:

On Dec 10, 9:00 pm, Sylvia Else<syl...@not.here.invalid>  wrote:

On 10/12/2011 9:33 PM, kreed wrote:

On Dec 10, 8:28 pm, Sylvia Else<syl...@not.here.invalid>    wrote:
On 10/12/2011 10:14 AM, David Eather wrote:

On 9/12/2011 10:56 AM, Sylvia Else wrote:
On 9/12/2011 4:23 AM, linnix wrote:
On Dec 8, 9:01 am, Fred Bloggs<bloggs.fredbloggs.f...@gmail.com
wrote:
On Dec 8, 1:50 am, Sylvia Else<syl...@not.here.invalid>    wrote:

The defrost timer in my fridge is failing, and given the cost of a
'genuine' replacement part, I was pondering the option of making
electronic timer driving an electromechanical relay.

It probably won't happen, but when I was looking at relay specs, I
found
that their ratings are usually specified as a highish reactive power,
and a much lower real power.

http://australia.rs-online.com/web/p/electromechanical-relays/1279550/

is typical, specifying in this case 300 W / 2500 VA.

I find this difficult to fathom. Imagine a purely inductive 2500VA
load.
So no real power being switched, but it would arc like crazy. What
am I
missing here?

Sylvia.

There are aftermarket universals better than the OEM
parthttp://compare.ebay.com/like/290638915750?var=lv<yp=AllFixedPriceIt...

There are plenty of relays you can salvage out of garage opener (12V),
microwave (12V) or furnace (24V). Add a micro or 555 for less than $5
and you are done. I am doing one for my furnace timer.

Not sure about getting a 555 to run at 1 cycle per six hours.

A PIC would no doubt do the job easily, but then I'd have to invest in
hardware to program it.

Sylvia.

Sylvia,

Try a PICAXE 08M2 - it costs $2.50 in one off's and programs in BASIC.
Software and examples are free fromwww.picaxe.co.uk
It is not uncommon for people totally new to the PICAXE have had them
running programs within 30 minutes of getting their first chip.

The only stuff you need to program one is a serial port (RS232 or TTL
level) and a resistor.

Interesting. Thanks.

I'm tempted to combine the timer with the thermostat, a replacement for
which I've been cursin..., er, I mean testing, today. (Sod's law
subsection 3.1 - a fridge must always enter defrost mode while a person
is attempting to adjust the upper and lower settings of a thermostat.)

Of course, I could just buy a new fridge.

Sylvia.

Depends on how old, and how good the current one is other than this
current problem.  New ones might be even worse :)

It would have to be at least ten, and it's been running all that time.

The big question, of course, is how much longer the compressor will
last, since it's probably not going to possible to source a replacement,
even if it would otherwise be economically worthwhile.

BTW, the wires are attached to the (mains-voltage) lamp socket by way of
spring clips. Seems a bit iffy to me.

Sylvia.

I remember a few years back there was one of these educational
programs on how things work, in particular household appliances.  They
actually went to a dump site where were were dozens of junked fridges,
and connected each one to power.  Almost all still cooled, but had
been dumped due to rust, broken shelves, seals etc or other similar
damage.  They said that the compressors were extremely reliable.

OK, i am going dumper diving.

...
As for that electronic aftermarket timer from Ebay that is 120v - if
you get one and open it up, you might find that it has either a
switchmode power supply or a series capacitor type supply.  You can
modify these fairly easily to run from 240v, or make up a small power
supply that you can mount in the back of the fridge.  For something
like this a linear power supply might be best, as linear ones are very
reliable.

Actually, a good source of relays are garage openers.  I have a spare
board with 3 240V/5A w 24V/5A coil.  I guess it needs open/close/on.

I have worked on a couple of newer Australian made ones here and now
they have no relays at all in them.  Other brands
might have, or older models that are being replaced.

A lot of the modern ones use butane as a refrigerant so may be they do
not want open contacts in the very remote case of leaks
I meant garage door openers :)
 
kreed wrote:
On Dec 13, 5:12 pm, F Murtz<hagg...@hotmail.com> wrote:
kreed wrote:
On Dec 11, 9:16 am, linnix<m...@linnix.info-for.us> wrote:
On Dec 10, 2:39 pm, kreed<kenreed1...@gmail.com> wrote:

On Dec 10, 9:00 pm, Sylvia Else<syl...@not.here.invalid> wrote:

On 10/12/2011 9:33 PM, kreed wrote:

On Dec 10, 8:28 pm, Sylvia Else<syl...@not.here.invalid> wrote:
On 10/12/2011 10:14 AM, David Eather wrote:

On 9/12/2011 10:56 AM, Sylvia Else wrote:
On 9/12/2011 4:23 AM, linnix wrote:
On Dec 8, 9:01 am, Fred Bloggs<bloggs.fredbloggs.f...@gmail.com
wrote:
On Dec 8, 1:50 am, Sylvia Else<syl...@not.here.invalid> wrote:

The defrost timer in my fridge is failing, and given the cost of a
'genuine' replacement part, I was pondering the option of making
electronic timer driving an electromechanical relay.

It probably won't happen, but when I was looking at relay specs, I
found
that their ratings are usually specified as a highish reactive power,
and a much lower real power.

http://australia.rs-online.com/web/p/electromechanical-relays/1279550/

is typical, specifying in this case 300 W / 2500 VA.

I find this difficult to fathom. Imagine a purely inductive 2500VA
load.
So no real power being switched, but it would arc like crazy. What
am I
missing here?

Sylvia.

There are aftermarket universals better than the OEM
parthttp://compare.ebay.com/like/290638915750?var=lv<yp=AllFixedPriceIt...

There are plenty of relays you can salvage out of garage opener (12V),
microwave (12V) or furnace (24V). Add a micro or 555 for less than $5
and you are done. I am doing one for my furnace timer.

Not sure about getting a 555 to run at 1 cycle per six hours.

A PIC would no doubt do the job easily, but then I'd have to invest in
hardware to program it.

Sylvia.

Sylvia,

Try a PICAXE 08M2 - it costs $2.50 in one off's and programs in BASIC.
Software and examples are free fromwww.picaxe.co.uk
It is not uncommon for people totally new to the PICAXE have had them
running programs within 30 minutes of getting their first chip.

The only stuff you need to program one is a serial port (RS232 or TTL
level) and a resistor.

Interesting. Thanks.

I'm tempted to combine the timer with the thermostat, a replacement for
which I've been cursin..., er, I mean testing, today. (Sod's law
subsection 3.1 - a fridge must always enter defrost mode while a person
is attempting to adjust the upper and lower settings of a thermostat.)

Of course, I could just buy a new fridge.

Sylvia.

Depends on how old, and how good the current one is other than this
current problem. New ones might be even worse :)

It would have to be at least ten, and it's been running all that time.

The big question, of course, is how much longer the compressor will
last, since it's probably not going to possible to source a replacement,
even if it would otherwise be economically worthwhile.

BTW, the wires are attached to the (mains-voltage) lamp socket by way of
spring clips. Seems a bit iffy to me.

Sylvia.

I remember a few years back there was one of these educational
programs on how things work, in particular household appliances. They
actually went to a dump site where were were dozens of junked fridges,
and connected each one to power. Almost all still cooled, but had
been dumped due to rust, broken shelves, seals etc or other similar
damage. They said that the compressors were extremely reliable.

OK, i am going dumper diving.

...
As for that electronic aftermarket timer from Ebay that is 120v - if
you get one and open it up, you might find that it has either a
switchmode power supply or a series capacitor type supply. You can
modify these fairly easily to run from 240v, or make up a small power
supply that you can mount in the back of the fridge. For something
like this a linear power supply might be best, as linear ones are very
reliable.

Actually, a good source of relays are garage openers. I have a spare
board with 3 240V/5A w 24V/5A coil. I guess it needs open/close/on.

I have worked on a couple of newer Australian made ones here and now
they have no relays at all in them. Other brands
might have, or older models that are being replaced.

A lot of the modern ones use butane as a refrigerant so may be they do
not want open contacts in the very remote case of leaks

I meant garage door openers :)
Did not see that but it may also be the case with the newer fridges.
 

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