[Lab] human powered art

Darcy Whyte darcy at siteware.com
Sat Jan 15 20:55:55 EST 2011

I guess another way to look at it is if I need 1000W to make toast. And it
takes 5m to make the toast. If we can get 50W out of a person, then they'd
have to peddle for 15m to charge a battery, then they could make the toast
in 5m. So it would take 20m to make the toast. (Assuming we've got a pretty
efficient generator and battery).

But then we don't feel the real load of making toast since we've spread it
out over 15m. I wanted to make the power in real time. I imagined that a
person would guess (wrongly) that they could turn the generator and make
toast easily. But when they try it they will be surprised that they can't
sustain since the toaster draws too much current. So then they'd get their
friends to help gang up on the machine.

So I was thinking of having some sort of spool with cable on it and people
could row (turning the spool), or even harness the cable to their hip and
run out for 20 feet, then return and do it again. If there were a long
enough spool so lots of people could be doing this action, then a team of
people could probably make the toast.

I've got some interesting ideas of how to have people turn the generator but
I want to start with having one that's efficient and the right size.

On Sat, Jan 15, 2011 at 8:45 PM, Darcy Whyte <darcy at siteware.com> wrote:

> Yeah, I think a stepper can be a good generator. But the problem I'm trying
> to solve is what size of stepper or electric motor would make a good
> generator for capturing electricity from a human. Apparently a human can
> average about .1hp. But can put out more power in bursts. So I was figuring
> that stepper might be too small.
> Do you think a couple of NEMA 34 motors is enough to capture energy that a
> person can generate?
> I think a car alternator is out since it needs electricity to generate
> electricity. I'm not sure their so efficient.
> Yeah, I figured for the toaster application we'd need more than a hp. I'm
> wondering if a NEMA 34 would be enough. Or perhaps a team of them (what size
> team?)
> Your numbers agree with mine on the number of people it would take. And
> that's part of the message in this art piece. The average person doesn't
> have a sense of how much electricity we use in terms of the work it's
> equivalent to (in terms we understand).
> So if it turns out it's 2 NEMA-34s to extract power from a human, I may
> need to look at about 10 of them in the toaster application.  (So people can
> team up to push the generators to make the toast.
> The page you made on human generators looks awesome. I'll go through those
> links and information.
> On Sat, Jan 15, 2011 at 6:12 PM, Richard Guy Briggs <rgb at tricolour.net>wrote:
>> On Fri, Jan 14, 2011 at 07:14:29AM -0500, Darcy Whyte wrote:
>> > I would like to make a human powered generator for an art project.
>> I've been wanting to build one for a while now...
>> > I am curious if a couple of NEMA 34 motors is large enough to capture
>> all
>> > the power that a human can generate.
>> My understanding is that a stepper is not the kind of motor that can be
>> used as a generator.  Wait!  I stand corrected!
>> http://www.thebackshed.com/Windmill/assemblyMini3.asp
>> What is most commonly used to generate DC is a commutated DC motor.
>> A car alternator will also work.  It is an AC generator with a
>> rectifier, but they tend to be a lot less efficient.  It also needs a
>> power supply bias to get started (say, a car battery under charge) since
>> there are no permanent magnets and it uses a field coil.
>> My understanding is that motors are typically 80% efficient, while
>> dynamos closer to 50%.
>> Do you have a link for your NEMA 34 motor specs?  I've seen anywhere
>> from 50W up to 500, so it sounds like those might work!
>> > I'm looking at a couple of applications.
>> >
>> > 1) To run a 120V toaster. I suspect this might need as many as 5 people
>> to
>> > peddle. Also to run a 60W incandescence bulb.
>> A toaster is going to need 3 top athletes (400W ea) or about 8 fit
>> adults (150w ea) to run.  For kids (50w ea), it is going to be more like
>> 25...
>> > 2) To charge a 12V battery.
>> One will work here, it'll just take longer...
>> I wanted to power a TV, or at least to power the "on" circuit.  Other
>> ideas we had was to use a human powered generator to power parade float
>> lights or moving parts.
>> > I'm suspecting that a stepper motor is a good candidate to make the
>> > electricity. I think the first part of the project is to make up some
>> BOMs
>> > that show what motor to use, the RPM that it would require and parts for
>> a
>> > rectifier and whatever else is necessary to operate in these
>> applications.
>> I've got lots of small ones, so I can try some tests and see.  I
>> wouldn't have thought they would work because the rotor I thought was
>> unmagnetized steel.
>> > Does anybody know of any existing projects or have any recommendations?
>> There are lots out there that I have tripped upon in the past...  I
>> threw together this page to summarize:
>>        http://tricolour.net/bicycle-generator.html
>> I just tripped on this site that may be of interest too:
>>        http://www.thebackshed.com/
>>        slainte mhath, RGB
>> --
>> Richard Guy Briggs               --  ~\    -- ~\            <
>> hpv.tricolour.net>
>> <www.TriColour.net>                --  \___   o \@       @       Ride yer
>> bike!
>> Ottawa, ON, CANADA                  --  Lo_>__M__\\/\%__\\/\%
>> Vote! -- <greenparty.ca
>> >_____GTVS6#790__(*)__(*)________(*)(*)_________________
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