Actually, there are many pieces of exercise equipment that generate their own power. Most of them don't offer a way to use any of the energy externally, they merly drain off the excess power through a rather large resistor. I bought an older one and found that it used a standard car alternator?!? Wow that makes things easy! They put a purpose built alternator in them that have dummy regulator chips (they only act as place holders, no circuitry inside). But, you can either trick the system to give you power using the existing circuitry (Like I tried to do), without schematics this becomes a tricky and time consuming task. The easy way is to disconnect the alternator from the onboard circuitry and install a simple regulator circuit of your own. Use a potentiometer (Variable Resistor) to vary the voltage and off you go! Now you can set the output voltage to charge any combination of batteries with a range of voltages. With a little filtering you can produce a stable output for charging cell phones and pda's, or just run a small fan to keep cool while exercising. Pretty neat I thought. The only problem with using an alternator as opposed to a generator is the need for a startup power source to give you an initial magnetic field to start power generation. If it has an alternator then it will also come with a small battery to do just that. Mine has an 8V lead acid, something small like 7ah or lower, don't need much to get the system started. A quick tap of a momentary switch takes care of that, just make sure you feed power back to keep this startup battery charged.
Neat stuff! There's an interesting (although not technical) video here describing one such gym in California.
I'd like to grab an old exercise bike one day and rig it up as a generator... It's always frustrated me to see exercise equipment plugged into the wall. I suppose taking AC power is simpler and likely cheaper, but it just seems like such a waste.
Interestingly, a couple of years ago my parents bought a new exercise bike that was self-powered. It worked great, but if you had to stop pedaling for just a few seconds, the whole system reset and you had to start your cycle over again. So they asked me if I could fix that. Well after a little probing I found the perfect spot to add a bundle of supercaps. Now you get several minutes of non-pedaling time with only a few extra seconds required at startup to charge the caps.
Neat stuff! There's an interesting (although not technical) video here describing one such gym in California.
I'd like to grab an old exercise bike one day and rig it up as a generator... It's always frustrated me to see exercise equipment plugged into the wall. I suppose taking AC power is simpler and likely cheaper, but it just seems like such a waste.
Interestingly, a couple of years ago my parents bought a new exercise bike that was self-powered. It worked great, but if you had to stop pedaling for just a few seconds, the whole system reset and you had to start your cycle over again. So they asked me if I could fix that. Well after a little probing I found the perfect spot to add a bundle of supercaps. Now you get several minutes of non-pedaling time with only a few extra seconds required at startup to charge the caps.