What should I know about pedaling speed when delivering power to a 12 volt DC television running at 15 Watts?
Hello. My name is Rachel and I’m a sophomore in high school. For science fair my group and i are building a bicycle powered television. We are connecting a permanent magnet DC motor as a generator to a 15 watt television. I’m confused on how exactly this works out. We wanted to change the gear ration between the bike wheel and the alternator and the mph that the person pedals. When we talked with my dad, he said that this wouldn’t work because the wheel speed has to be constant. I thought that if we had a mph measuring device and roughly three different gear ratios we could determine how fast a person would have to pedal with each different gear ratio to generate the same voltage. My dad said something about how we need wattage, not voltage. I thought that if we just had to determine the voltage??? So, then my dad brought up the idea that we could measure RPM per watts for each different BIKE gear. (not the gear ratio between the bike and the generator.) This would give us a certain RP
