Relay contact ratings.

Though on further examination, by the time you've paid the higher cost for the chip, the postage from the UK, and either bought or made the cable, it's considerably cheaper just to buy a programmer from a local supplier.

PICAXE is probably good for people who've little or no experience in programming, particularly at assembler code level.

Sylvia.

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),

Get the PICKIT 3 for $7 more, in case you want to program PIC24 or PIC32. Not sure if PICKIT 2 can program them.

On Thu, 15 Dec 2011 10:22:50 +1100, Sylvia Else wrote:>>

I did, but I've formed the view that if I were going to do this, I'd include the thermostat as well, and choose a better point in the thermostat hysteresis at which to start the defrost cycle, rather than having a random relationship as is the situation now.

Sylvia.

Yes, we should have a thermistor for the room temperature, one for the inside temperature, one at the beginning of the heat exchanger and one at the end. This way, we can measure the temperature gradient based on compressor and heater run time, and control them. This should reduce unnecessary heating and cooling cycles.

--- And, for the ASCIImatic (thanks, Steve :-):

. +V . | . 4060 Vcc +----+ . +------+ | U3C |K | O---->C . +-887K--|Rs MR|-------|------+-A / DIODE COIL]- -|K1 . | | | | | Y-+ | | O-> |NC . +-442K--|Rt | 10k +-B | +----+ | . | | | | | | | +-------->NO . +-0.1µF-|Ct Q13|--10nF-+ +-A | C . +------+ | | Y-+--1k--B 2N2222 . U1 | +-B \ E . U3A +-A | U3D | . 4081 Y-+ GND . +-B | . | | . | B-+ . +-Y U3B . | A-+ . 4060 | | . +------+ | Vcc | . +-976k--|Rs MR|-------+ | | . | | | | | . +-527k--|Rt | 10k | . | | | | | . +-1.0µF-|Ct Q13|--[10nF]--+---+ . +------+ . U2

-- JF

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The US Department of Energy sponsored research into improving refrigerator efficiency. Here are a couple of starter links:

The main thing was increasing insulation from 1/2" to 2". Adaptive defrost is mentioned too (in the 2nd link).

The ultimate in efficient refrigerators is a chest freezer, home- converted into a fridge.

-- Cheers, James Arthur

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The chest freezer works better--the insulation's thicker. I might do one one day. Or not.

Turning an upright fridge sideways would be a lot more work--orienting the coils, for one thing. You could just strap some 4" foam insulation board on a standard fridge--that's damn ugly, but it's green :-) I think I just qualified for a green subsidy. Or a DOE grant.

-- Cheers, James Arthur

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Be carefull about using MOVs. It wears out over time, from subjected surges. So when your are not home, it may blow without your knowledge, and the next time you have a lightning surge it doesn't protect at all. Better to use Transient Voltage Suppressor, Tranzorbs....

Cheers

Klaus

no, I means less.

It's a heat pump. and like a water pump, it uses less electricity when pumping a smaller head.

it'll only take it a few seconds to get the temperature down to freezing, but for a few seconds it's easier than normal.

if you let the defrosting heat escapes from the evaporator into the contents of the fridge it's harder to call it back.

Certainly nore "more".

I'd look at using valves from/for a dishwasher or washing machine they're designed for hot water and indoor appliances.

how are you planning on stopping the water from freezing?

887K?

I'd do it like this:

links:

Refrigeration systems generally rely on gravity to avoid trying to compress liquid, which is somewhat more difficult to do. Running one on its side is not guaranteed to work.

Cheers

Phil Hobbs

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I always have a fuse with the MOV. If it blow (usually short out), it will take out the fuse as well.

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Good question. Perhaps i need a small NG heater instead.

I think it's guaranteed not to work unless you rotate everything, which is what I meant to insinuate. If convection-cooled, there's also the problem of convection cooling not performing as designed -- it won't "draw."

More to the point, besides having to bend to the floor to get your stuff, a sideways-refrigerator's contents (and cold air load) dumps onto the floor every time you open the door. And, the contents would be ready to spill, since all the shelves would be sideways too. You'd have to put it on its back, which has even more problems.

The chest freezer's compressor is oversized for ultra-insulated refrigerator service, but I suspect less oversized and a better and more efficient match than a standard refrigerator's compressor.

So, the converted chest freezer wins on all fronts.

OTOH, 4 inches of judiciously applied pink foam beats most of these problems, and it's extra-ugly. :-)

-- Cheers, James Arthur

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Chest fridge is hard to locate stuffs. Even with upright fridge, foods are often hidden and spoiled. Perhaps the upright fridge should be compartmentalized with clear drawers, or even multiple doors, to minimum cold lost.

links:

If you stick it on a "harvest gold" refrigerator, it would be a big improvement.

Cheers

Phil Hobbs