Hi,

I would like to build a really simple display of human energy for a local school.

The idea is this, a vertical row of low voltage incadencent or halogen bulbs, each around 10watts.

As the child starts pedalling and produces <10w the first bulb is lit, then >10w <20w the second and first bulb are lit and so on. I like to have around 10 increments.

The generator is MY1016 DC PM motor that can produce upto 200watts.

I have little to no electronic experience and was wondering if there is a simple way to do this.

Thanks
Colin

 

It depends on what your definition of "simple" is. Basically, a circuit would need to measure the output power (which, in itself, involves making two independent measurements), then switch amongst 10 different switches to get the pattern you want. The load can be constant, so then you just need to measure the current (and you can run the light bulbs off another source of power so the user doesn't have to power the light bulbs too). This is not terribly challenging with some comparators, resistors, and transistors/FETs for switches. It's likely that one of the experts here would design most or all of the circuit for you.

However, given that you have no electronics experience, you might want to start with a simpler task, such as constructing a constant load. A simple analog meter with a shunt (see the DC electronics tutorial) could measure the current and be used to show the person providing the power how hard they were working.

In the 1980's, I made a device for a local science museum (actually, the forerunner of the museum) that used a DC servo motor and a crank, exactly like you want to do. I hooked up a computer and a voltmeter to measure the output voltage and the voltage across a shunt and, thus, the power being output by the person cranking the motor. The person pressed a button to go, then the computer program measured the power output over time and plotted this as a function of time. The neat part was that I used an HP 7550 plotter, which picked up a piece of paper, made the plot, then spit it out for the user so they could take the plot away with them. People loved watching the plotter as much as they liked playing with the motor.

This would be much easier to do today with an inexpensive printer and a USB measuring device attached to a cheap PC or laptop.

 

Perhaps the OP could make something out of the LM3914 or LM3915 circuit or something simelar. With a constant load that it could work out. Remember that a light bulb is not a constant load.