LED generator

After finding out that a piezoelectric disk has enough juice to light an LED I made a generator.

I think this concept could very well work much better than those cheap flashlights that you crank. They have either batteries or magnets and are quite heavy. I think one of these could be made with lots of LEDs to make a useful flashlight that is very light.

Either way, it is a fun experiment. ūüôā

Piezo Generator

I’ve been thinking of ways of creating interactivity with LEDs.

One of the issues you run into is controlling them. You can control a few with an Arduino easily but when you have a lot of them it starts getting messy pretty fast.

Something  just dawned on me.  I happen to have a piezoelectric disk so I put an LED against it and I was totally amazed that there was enough current to light the LED! So I soldered it and tried a few simple experiments.

So an LED can be activated mechanically. Further, this could prove to be a great way of harvesting small amounts of electricity from mechanical systems.

Ed Begley makes toast

The actual toast from experiment. ūüôā

Steve of Canadian Energy Issues brought this CBC Podcast (Skip ahead to 00:24:45) to my attention. Ed Begley, actor and environmentalist makes toast from his pedal generator.

I know a toaster needs a lot of power so wanted to work through the numbers.

Okay, I’m making toast as I write this. My toast has been going for a minute as I type this sentence.

I found a table of appliance consumption (toasters take 800-1500 Watts so 1000 Watts seems like a good number for arguement).

03:15 Dinnnnnnnnnnnnnnnnnggg! I learned something. Toast takes about 3 minutes from cold.

Ed pedals 15m to make toast.¬†That’s 5x longer than the 3m cook time. So he can put out 1/5th the toaster requirement. In other words it will take 18m to make the toast. Fifteen minutes of frantic pedaling (energy being stored) and then 3m to run the toaster.

So he needs to pedal at 200 Watts (1/5th of 1000 Watts) for 15m if he has an efficient electricity storage system attached to his bike.

To try and see how reasonable that is lets do some comparisons. A person can make about 1/10th horsepower over extended periods. A horsepower is about 746 Watts so 200W is about 1/4 horsepower.

1/4 hp for a short period seems plausible to me. In fact I’ve seen projects that require even more human input.¬†The Gossamer Albotross pedal powered plane requires 0.4 hp and a human pedaled it across the English Channel in just under 3h.

Let’s put 200 Watts into some familiar terms so we can¬†“Feel the Power”.

A horsepower is 550 foot-pounds/second (you can lift 550 pounds one foot in one second, or one pound 550 feet in one second). We need to do 1/4 of that so we’re talking 138 foot pounds per second.

Fifteen minutes of pedaling is 900 seconds which means he is doing 124,200 foot pounds of work.

I just googled Ed to see a picture of him to guess how much he weighs. I’m very scientific. ūüôā¬†Um, okay he looks like a thin/fit guy so let’s give him 175lb. I understand he’d tall so perhaps we should kick another 15lb? Perhaps 190lb?

To “Feel the Power” we need to divide 190lb into the 124,200 foot pounds and see how high to climb stairs in 15m. That comes to 654 feet. That’s 65 floors in 15m.

So to get a feel for how much this is, it’s a matter of finding a 70 floor building and running up the stairs in about 15m.¬†That’s 4-5 floors per minute.

So it looks plausible, but don’t be fooled into thinking it’s easy. This calculation also suggests that it would take 5 people to make toast in real time using 1/4 horsepower each.

Honda Power Supply


I’ve been eyeballing gas powered power supplies over the past while.

I was thinking it could serve a lot of purposes. At any sort of trade show or travel, I’d be guaranteed electricity. It could be backup power for some stuff at home. Seems like an all around cool gadget.

There are cheap two stroke ones (probably noisy too). Very affordable. But I suspect 4 stroke is the way to go on these. Such as this Honda I came across yesterday.

Those things are about 800 bucks. Being a Honda I’m sure they are quiet and reliable. Probably has a long run-time per tank too. I think if you go non-Honda you get it down to 400. And if you go 2-stroke, you get it in half again.

I guess I’ll keep eyeballing for now.

Mounting a generator on a pedal bike


Looks like my friend Sanjay will be the first guinea pig for generating electricity from human power.

He has an exercise bike which looks great for getting some testing in on some generators.

I should have a generator in hand today if all goes as planed.

I will take a look at mounting something on the bike.

I guess we need some nice loads for the first tests.

Anybody have anything that will run on 12-24vDC or there abouts?

Any suggestions?

I’m betting we will get 12v or better since the first generator I am getting is a 24VDC motor from a go-kart application.

Using a Stepper Motor as a generator

Pedal-A-Watt Stationary Bike Power Generator

I would like to make a human powered generator for an art project.

Challenge: I am curious if a couple of NEMA 34 motors is large enough to capture all the power that a human can generate.

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.

2) To charge a 12V battery.

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.

Does anybody know of any existing projects or have any recommendations?

Richard Guy Briggs brought the Pedal-A-Watt Stationary Bike Power Generator to my attention (in the picture). I think if we could figure out what motor it is they are using for a generator, that might be the thing to get.

I just added another link below where the motor looks the same. They’re calling it an Oatley DC motor.

I found it here for cheap. Here’s another.

A nice 500W.

A nice 350W.

Here’s a DIY 1000W one.

Another DIY using Volvo parts (more).

I noticed they claim the Oatley works well in a windmill (which would be low RPM). Well that one claims it only got to 5V, but that’s pretty low RPM so this might be promising.