Why Three Rails?



You can still get them. These are the "sharper image" car units. they work by allowing the gas to expand in the frige (cool) and compress it outside. Gas or electric is used to compress.
Dugan's bread had the cards for the window. Yellow with a big D.
Jim Stewart
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With regard to non-electric 'fridges, I think that you could get ones that worked off kerosene, using the 'absorption' (or was it adsorption?) process, which I'd have to look up to see how it worked. Regards, Bill.

old
I
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On Sat, 30 Jul 2005 00:43:20 -0500, Jim Stewart wrote:

Whaaa?? Sharper Image??? the Thomas Kincaid of the tech world?
How about Servel, maybe Norcold?

Actually, they boil ammonia using a heat source - and can use electricity for that, but not to run a motor to power a compressor. Running in gas mode most do need a little electricity to run a positive draft fan for the boiler. The whole idea is to NOT use electricity. I've been in folks' houses that are off the grid, and they don't want to waste precious power out of their (typically) photovoltaic panel fed battery banks running a compressor.
http://www.rvmobile.com/tech/Trouble/coolunit.htm http://www.backwoodshome.com/articles/hackleman56.html
--
Steve

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Gas (propane, but natural gas would work AFIK) powered refrigerators were (I'd guess they still are) common in motor homes. Perhaps these days they all have generators to supply 115 volts, but back in the 1970s and 1980s at least, they all had dual power fridges, that ran on gas or 115 volts.
We used gas when on the road or away from AC, and switched to AC when we were staying for any period of time somewhere. Compared to the water heater or heaven forefend the furnace, it used very little gas.
Large units for home use are probably very rare.
Regards,
DAve
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On Sun, 31 Jul 2005 05:29:59 GMT, DaveW wrote:

Actually, perhaps no more rare than PV fed battery banks. Servel and Norcold manage to keep making them. They are expensive though, so relatively rare compared to Kenmore or Frigidaire or KitchenAid*
* why those doofuses put a fragile appliance bulb just inside the front top, right where stuff being lifted off teh top shelf can bang into it, with NO plastic cover over the bulb, I'll never know; a real piece of design stupidity
--
Steve

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Steve Caple wrote:

Also WIDELY used in the "RV" industry for small refrigerators in trailers and motor-home vehicles. These don't work terribly well, but will keep the 'fridge' reasonably cold, though making ice is difficult. Many will operate off either gas, 12 VDC, or 115 VAC. All they need is a heat source, be it gas flame, or electric heating coil. No moving parts. None I've seen or owned used any electric fan. They do have a sizeable radiator that must be allowed free air circulation. My experience has been that they work best off 115 VAC or gas, but poorly off 12 VDC.
Dan Mitchell ===========
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Yes, that is what I had. Used to plug it into house overnight and then into car cig lighter. would form ice....
Jim Stewart
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Bob May wrote:

generate as

standard
Actually, selenium rectifiers were a great leap forward compared to the copper oxide rectifiers which preceded them and which only the telephone company could afford. They weren't very good rectifiers and the telephone company didn't like them, but used them because they needed DC and the only other ways to get DC pre-WW2 were from primary batteries and motor-generator sets.
Bob Netzlof
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DC power is still in use in many LA movie studios, as lamps operated on DC last longer and are quieter in use than lamps on AC.
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They also need DC if they are going to run arc lights.
Jim.
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snipped-for-privacy@aol.com wrote:

There are some advantages to DC, but the difficulty in 'transforming' voltages and the losses in long distance transmission far outweigh them. Well before W.W.II most communities and utilities had switched to AC for those reasons. There were some 'hold-outs' however. The smaller systems using DC could use big banks of batteries for inexpensive back up power, as you describe for the phone companies.
AC systems had NO readily available back up power, except for more generators (uneconomical). Modern 'inverters (DC to AC) were NOT available. Only motor-generator ('MG') sets could do DC to AC conversion, and they were very inefficient.
Similarly, only MG sets could do DC to DC voltage conversion acceptably. Very small scale downward conversion could be done with resistance grids, but this is extremely wasteful. Upward voltage conversion required an MG set. Look at most W.W.II military radios and you'll find several small MG sets providing the various DC voltages needed by the radio. Some such MG sets could simultaneously produce several different DC voltages (different windings in the generator part). They were heavy, noisy, and troublesome, but there was no alternative at the time.
Dan Mitchell ==========
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Daniel A. Mitchell wrote:

operated on

them.
for
systems
power,
acceptably.
find
different
heavy,
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Also, 027 is DC, at least as far as Lionel engines go. You can of course hook up an AC transformer and run AC engines on 027 track. This is something that can catch the unwary on eBay.
Robert wrote:

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RRGrandad wrote:

The VAST majority of Lionel O-27 locos are AC, not DC, and always have been.
Only some low-end sets were made as DC, accompanied with an appropriate DC power pack that would not operate the regular AC locos. These DC sets were NON-standard, even by Lionel's standards. This can be VERY confusing to anyone buying a set at a discount store or flea market, and not understanding what they are getting.
When I worked at a hobby shop, for many years, people were always bringing in the DC locos (that they got somewhere else) and trying to get them 'fixed' so they would operate with their other Lionel AC equipment. We sold both, but were always careful to let customers know what they were buying if the wanted a Lionel DC set.
Dan Mitchell ==========
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O-27 is AC , not DC. DC is used with all of the Lionel stuff to do the reversing of the loco.
-- Why isn't there an Ozone Hole at the NORTH Pole?
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No. Reversing was accomplished by interrupting the current. Low voltage DC was used to activate the whistles. Exception to prove the rule - there was a special two train set offered around 1940 where one train was reversed the normal way and the other by DC using a modified whistle relay. This was called "Magic Electrol". Gary Q
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Geezer wrote:

That's right. The earlier Lionel stuff would run on pure DC, if desired.
The electric whistles in the locos were probably the first things thet *REQUIRED* AC. Even then, the train would still RUN on DC, but you couldn't blow the whistle.
They occasionally tried all sorts of things. The peak of this was the post W.W.II set that used various AC frequencies to control the trian. It was a primative version of "Command Control", and used tuned resonant relays to select between the various control frequencies. It did work, but NOT very well. The average person, including Lionel repair personnel, couldn't keep the things working. The sets were soon pulled off the market. These sets are a big collector's item these days.
Dan Mitchell ==========
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OK, how DID that whistle thing work?
How did it know it got a burst of DC in the AC, and why wouldn't it blow all the time if the train was running on DC? Simply, what was the circuit involved?
--
Bill Kaiser
snipped-for-privacy@mtholyoke.edu
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snipped-for-privacy@mtholyoke.edu wrote:

What I SHOULD have said was that the whistles required BOTH AC and DC to work properly. On the other hand, the loco motors and reversing e-unit sequencer couldn't care whether they got AC or DC to work.
Most used an internal relay to activate the whistle. On the usually 60 Hz AC track power the relay would TRY to activate 60 times per second, first one way, then the other. The result, due to the mechanical inertia of the relay, was NO relay motion at all (but usually some buzzing sounds).
Adding a shot of DC with the whistle button on the transformer electrically 'biased' the relay inone direction sufficiently to cause it to trip, closing a contact, that actuated the whistle motor.
So, yes, on pure DC the whistle would likely try to blow all the time. You just had to disconnect the whistle in that case. The train itself would run fine. Many of the really early sets, those most likely to be run under DC conditions, didn't necessarily have whistles anyway.
Dan Mitchell ==========
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snipped-for-privacy@mtholyoke.edu wrote:

That's the problem... the whistle would blow continuously. It had to be disabled by disconnecting a wire in the tender.
There is a DC relay inside the tender, or loco body for diesels.
On steamers, the relay contacts completed the circuit to provide track power to the whistle motor. Compensating windings in the controller ensured a voltage & current boost to provide a little extra power for running the whistle motor in addition to the engine. The loco could be wired to provide the current instead to an electromagnetic release coupler
On diesels, the relay completed a circuit to connect a dry cell (sic) battery to a bicycle-type horn, producing that magical Lionel "bleating".
The locos could be wired to provide the current instead to the reverising "e-unit" (Magic-Electrol) or an electromagnetic release coupler or couplers (Teledyne). See:
http://makeashorterlink.com/?J6303298A
For a better description & excellent wiring diagrams.
Rob
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