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addendum to the rules... external power sources

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  • addendum to the rules... external power sources

    so a few folks in the past have asked me about beverage cooling contraptions that rely on electricity. the contest rules have historically stated "all devices must be entirely self-sufficient (in particular, they should not require use of an electrical outlet)" but just recently one contestant posed the following argument to me...

    "Seeing as how technically the ice-powered coolers aren't self-sufficient (the ice is made elsewhere [using conventional, modern power sources]) can there be a modification to the rules for peltier-based coolers?"

    simply on the grounds that the above statement is one of the most innovative arguments of creative yet totally consistent logic i am bending the rules this year and allowing this person (and anyone else who wants to) to employ external power sources (that's assuming we can get an extension cord out there, i'll have to check on that)

    bear in mind, the rules as i have now modified them read "all devices must be as self-sufficient as possible (in particular, people should try to avoid the use of an electrical outlet)"... so folks who have long orange wires as part of their design may find themselves ranked slightly below others who employ something totally self-contained. if you need lots of power, points would be awarded a great deal for finding a totally independent (yet still portable) solution. (i even tried to cobble together something that would run on a super-small gasoline generator that i was making with a chainsaw engine just as a proof of concept.)

    i think that next year perhaps i'll split things into two categories... those that require external (outlet-style) power to operate and those that do not. this year, all players are in the same field but fully-independent and self-supporting contraptions will have an advantage.
    "I'll admit I had an OiNK account and frequented it quite often… What made OiNK a great place was that it was like the world's greatest record store… iTunes kind of feels like Sam Goody to me. I don't feel cool when I go there. I'm tired of seeing John Mayer's face pop up. I feel like I'm being hustled when I visit there, and I don't think their product is that great. DRM, low bit rate, etc... OiNK it existed because it filled a void of what people want."
    - Trent Reznor

  • #2
    Re: addendum to the rules... external power sources

    Originally posted by Deviant Ollam View Post
    ... (in particular, they should not require use of an electrical outlet)"
    The Spirit of your contests has been for ways to chill beer when far away from the conventional resources...

    If at the TBBQ, or at the chillout space, you could impose a limit on common AC by letting people use 110 Volt AC if they manage to bring a power inverter and gain access to a car to plug in the 12 Volt DC to 110 Volt AC Power inverter. This also limits the number of amps (and watts) their device can consume.

    Technically, a car could pull up to get close to both locations, and tailgate parties, beach parties and desert parties often include vehicles present.

    :-)
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    • #3
      Re: addendum to the rules... external power sources

      Inverters aren't really the solution since peltiers run on DC. It's criminally inefficient to go DC-AC-DC. Peltier-based coolers *could* run on a stack of car batteries but I really hate it when my vacations end in jail time for grand theft lead-acid.

      If somebody wants to volunteer to drive their car up to where the party is... and people want to tolerate the driver revving the engine to near redline.. and they're ok with me dissecting the alternator (and possible installing a second one)...

      :)

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      • #4
        Re: addendum to the rules... external power sources

        Originally posted by bloofar View Post
        Inverters aren't really the solution since peltiers run on DC. It's criminally inefficient to go DC-AC-DC. Peltier-based coolers *could* run on a stack of car batteries but I really hate it when my vacations end in jail time for grand theft lead-acid.

        If somebody wants to volunteer to drive their car up to where the party is... and people want to tolerate the driver revving the engine to near redline.. and they're ok with me dissecting the alternator (and possible installing a second one)...

        :)
        There are enough people at Defcon that are mechanics and hackers that I would not be surprised to see an entry that is part of a car that pulls up to the chii-out space.

        Attaching to the electrical output of a car (Through inverter with AC, or by battery with DC, or from alternator tap as AC) would seem to work with improvised cooling at remote locations. [Maybe someone can attach a generator to their car to get DC current that way, too.]

        I'm was trying to offer suggestions that would avoid any attempt to connect to hotel power, so demos might be possible at the tbbq too.

        Didn't one team demo at the TBBQ last year?
        Last edited by TheCotMan; 07-15-2007, 10:26 PM.
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        • #5
          Re: addendum to the rules... external power sources

          I'm not sure how this has not been discovered before. But this guy has us all beat, unfortunately. In every way. good god.

          http://www.asciimation.co.nz/beer/

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          • #6
            Re: addendum to the rules... external power sources

            Originally posted by TheCotMan View Post
            There are enough people at Defcon that are mechanics and hackers that I would not be surprised to see an entry that is part of a car that pulls up to the chii-out space.
            check of the link i posted above.. that's pretty win.

            Originally posted by TheCotMan View Post
            Attaching to the electrical output of a car (Through inverter with AC, or by battery with DC, or from alternator tap as AC) would seem to work with improvised cooling at remote locations. [Maybe someone can attach a generator to their car to get DC current that way, too.]
            Maybe it's coincidence but this week I managed to kill the alternator on my truck (@#$!ing ham gear). I've not replaced mine yet and I'm not up on how alternators work, but wouldn't the output of an alternator have a full-wave rectifier on it? I mean you could tap it before the rectifier to get AC but as an alternator is wired from the factory, wouldn't the output be DC?

            Originally posted by TheCotMan View Post
            I'm was trying to offer suggestions that would avoid any attempt to connect to hotel power, so demos might be possible at the tbbq too.

            Didn't one team demo at the TBBQ last year?
            I'm going to try really hard to be at the tbbq this year. I'd be all for trying to chill beer from a car battery if somebody brings jumper cables.

            I would really prefer not to run on AC. The Astron power supply I'm using right now probably won't enjoy the desert sun at all. Plus if we have a ready source of DC available (like a battery) then we don't have to worry about the inefficiencies of a PSU.

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            • #7
              Re: addendum to the rules... external power sources

              Originally posted by bloofar View Post
              Maybe it's coincidence but this week I managed to kill the alternator on my truck (@#$!ing ham gear). I've not replaced mine yet and I'm not up on how alternators work, but wouldn't the output of an alternator have a full-wave rectifier on it? I mean you could tap it before the rectifier to get AC but as an alternator is wired from the factory, wouldn't the output be DC?
              Usually, output leads are DC. But there was mention above to cracking open the alternator, which would suggest an attempt to gain access to the AC before it is transformed., and why I mentioned AC with respect to the alternator.

              If I recall correctly, alternators are AC, generators are DC, but a car's alternator include extra circuits to transform the AC to DC. This is why I think alternators for cars include "automotive" as a word preceeding "alternator" -- but this is just a guess.

              [Edit: added]
              Actually, it looks like both, internally generate AC, which is converted to DC in cars.
              Last edited by TheCotMan; 07-19-2007, 10:06 AM. Reason: typo, and vs an
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              • #8
                Re: addendum to the rules... external power sources

                Originally posted by TheCotMan View Post
                would would suggest and attempt to gain access to the AC before it is transformed., and why I mentioned AC with respect to the alternator.
                Ah sorry I missed that.

                Originally posted by TheCotMan View Post
                If I recall correctly, alternators are AC, generators are DC, but a car's alternator include extra circuits to transform the AC to DC. This is why I think alternators for cars include "automotive" as a word preceeding "alternator" -- but this is just a guess.
                I replaced the alternator in my truck last night / this morning. Would have been a lot easier if the A/C wasn't there (or if I could remove the that annoying plumbing that kept me from removing the fan box). Naturally, I took apart the old one before I sent it back for the core refund. (Curiously some of the manuals I have for my truck refer to it as a generator, some as an alternator). The mechanical bits do in fact generate AC and there's a full-wave rectifier at the back of it (4 large diodes wired in a bridge configuration).

                There was nothing visibly wrong with the old alternator so it was probably a break in one of the windings.

                Originally posted by TheCotMan View Post
                That's a really good page.

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                • #9
                  Re: addendum to the rules... external power sources

                  Originally posted by bloofar View Post
                  Ah sorry I missed that.
                  I could have been more descriptive, but I've been trying to keep the number of words used in my posts down to a level that doesn't cause people to skip them.

                  I replaced the alternator in my truck last night / this morning. Would have been a lot easier if the A/C wasn't there (or if I could remove the that annoying plumbing that kept me from removing the fan box). Naturally, I took apart the old one before I sent it back for the core refund. (Curiously some of the manuals I have for my truck refer to it as a generator, some as an alternator). The mechanical bits do in fact generate AC and there's a full-wave rectifier at the back of it (4 large diodes wired in a bridge configuration).
                  I had a Toyota Pickup before the Tacoma series, and those were really easy to work with. I replaced the alternator on that guy a few times, until I tracked down an intermittent short circuit to ground on the wiring harness. (Lots of hours of work there.) No AC, No power steering, No Power brakes, nothing extra really-- this made adding and removing the alternator a breeze. 10 minute job if I had all the parts and tools present.
                  You seem more mechanically inclined than me though, as I never did replace the core with a rebuilt-- I just bought new or reconditioned whole alternators.

                  There was nothing visibly wrong with the old alternator so it was probably a break in one of the windings.
                  Or a short. ;-)

                  That's a really good page.
                  Yeah, it was pretty good. Google helped me find it. I remember being told the difference between an alternator and a generator many ages ago, before I had a slightly better understanding in electronics. this thread caused me to start wondering how a rotating device like (DC) generators could generate DC. I could not envision the internal workings of such a system without an some transformation system. Now I know. :-)
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