HARDWARE:
Degu: Provides energy to the system.
"Cheech", a 3-year old male Degu. Eats a small handful of grain, a big pinch of dry Oatmeal, and a small handful of Hay each day. Likes a Peanut in the shell every few days as a treat, but is VERY possessive of his treat. Also likes a small piece of raw Sweet Potato every other day. Should produce a DeguLoad of power when coupled to the correct system. Also provides an ongoing supply of affection.
Wheel: Transfers energy from Degu to Generator.
"Giant 12" Comfort Wheel" by Pets International. Made in USA. $14.00 or so at Pet Smart.
We chose the wheel to be SAFE for Cheech to run in. Wire type wheels are UNSAFE, the poor critter loses his footing and bruises the heck out of his leg, possibly breaking it. This wheel is SAFE, as it has a solid running surface, no danger to his legs and feet. The wheel wobbles and rattles on its original mount, but shortly it will be mounted on a solid shaft and ball bearings.
Generator: Converts Mechanical Energy to Electrical Energy.
For initial experiments, I will be using a small permanent magnet stepper motor as a generator. It is moderately efficient at turning slow-speed mechanical energy into electrical energy, and I already own a bunch of them, so it is FREE. Initial experiments say the Stepper motor should produce output pulses in the range of 2 Volts and as much as an Amp. We shall see.
Later I plan to build a permanent magnet alternator for the job, hopefully achieving much higher output for the same amount of Degu input.
Rectifiers: Break AC power into pulses of DC power.
The stepper motor produces AC output, so will need rectified. Normal silicon diodes have a forward voltage drop of about 0.7 V, pretty expensive for such a low voltage generator. Schottky rectifiers have a voltage drop of 0.4 V, a substantial increase in efficiency. More on that as the project progresses.
Capacitors: Smooth the DC pulses into a more useful form.
The pulses of DC coming from the rectifiers will be more useful if we smooth them into fairly clean DC, so a capacitor or two is in order. I'll determine correct values after I have a better understanding of the current and voltage we are dealing with. I should have something appropriate in my junk box. Well, it's more than a "Junk Box" it's more of a "ROOM FULL" of electronic components.
DC-DC Converter: Provide correct voltage to charge batteries.
The voltage available on the Capacitors will be about 2 Volts, and we will be using a battery that requires 13.8 to 14.4 Volts to charge. A MAX1771 switch mode DC-DC converter from Maxim will efficiently convert the 2 Volts available into the 14 Volts we need to charge the battery.
Battery: Store the electricity.
The bursts of electricity available from a Degu running in his wheel are only available when he is running. He likes to run a bunch, but not ALL the time. We will store the electricity in a 12 Volt Gelled Electrolyte Lead-Acid Battery for later use.
Load: Use the electricity.
To be decided. Taking suggestions. Best thought so far: White LED nightlight. Worst thought so far: Siren.
Monitoring: Knowing how much electricity is being produced.
A PIC Microcontroller will monitor the battery's voltage and current as it is being charged, and calculate Power from this. P = I V I've had a lot of fun with the 16F88 microcontroller, but it's a bit limited for this job. I plan to have a LCD display for monitoring things, so a few more pins would be nice. The 16F877 has served me very well on a bunch of projects, but maybe it's time to move up to the 18F series by MicroChip, so I'm leaning toward the PIC18F452. I got a batch of them at bargain prices on eBay a while ago, so that makes them even more appealing.
The PIC chips have a 10-bit Analog to Digital Converter with a range of 0 to 5 VDC. That provides resolution of 5 miliVolts, should be more than needed for this project. They also have a UART built in, so can communicate easily with a serial port on a Computer.
Computer: Organize data into useful format and upload for the World to see.
I've got a computer here that's connected to the Internet and on all the time, so it seems like a great candidate for the job. It has an available Serial Port, so communicating with the PIC will be simple. I'll be writing the software myself , and plan on having GIF format graphs of Hourly, Weekly, Monthly and Annual electric production. I'll likely also throw in Temperature and other things as they come to mind.