Hand Crank Generator

[The Roberto]

I'm trying to rig up a series of lights to a hand crank generator. The
idea would be to have lights turn on when different voltages are reached
by the generator. I've been able to do this using opamps, but we're
trying to do this without any external power sources. Is this possible?
Thanks for any help.

Roberto

 

[CFoley1064]

Subject: Hand Crank Generator

From: The Roberto [email protected]
Date: 4/19/2004 11:40 AM Central Standard Time
Message-id: <[email protected]>

I'm trying to rig up a series of lights to a hand crank generator. The
idea would be to have lights turn on when different voltages are reached
by the generator. I've been able to do this using opamps, but we're
trying to do this without any external power sources. Is this possible?
Thanks for any help.

Roberto

Hi, Roberto. You're asking for something that's doable, but you haven't given
nearly enough information. Offhand, I'd say that, as long as you don't expect
anything to light up below about 3V or so, you should be OK. A few questions:

* AC or DC voltage?
* How much current can you afford to spend on the lights? How much current can
your hand crank generator produce?
* Incandescent or LED desired/required? If high voltage, is neon an option?

There are a lot of good analog meters which will give you an indication without
all the wiring, and give you greater accuracy. One place to look is Surplus
Sales of Nebraska, which has analog DC meters for around $20 USD. That might
be a better way to go.

http://www.surplussales.com/Meters/MtrDCVoltsmain.html

Good luck
Chris

 

[John Fields]

I'm trying to rig up a series of lights to a hand crank generator. The
idea would be to have lights turn on when different voltages are reached
by the generator. I've been able to do this using opamps, but we're
trying to do this without any external power sources. Is this possible?
Thanks for any help.

 

[The Roberto]

It can crank in AC or DC (just a switch of a magnet). I measured it to just a few
mA and at a plenty fast crank I get out about 12V. Incandescent lamps are
preferred to LEDs and these lamps are the only thing that is going to be powered.
This project is going to be an exhibit to show kids about energy use and give them
the idea that it takes a more effort to generate more electricity, so it has to be
done in some more spectaular way than just a panel meter (just following orders on
this one, a meter would be fine by me)

I suppose I would want the lights to start turning on at around 4V then 6 and 9.

Thanks,

Roberto

 

[jtech]

I'm trying to rig up a series of lights to a hand crank generator. The
idea would be to have lights turn on when different voltages are reached
by the generator. I've been able to do this using opamps, but we're
trying to do this without any external power sources. Is this possible?
Thanks for any help.

Roberto

play with adding resistors on the each bulb to control its current so they
light with different voltage, might also add a zener arrangement to limit to
lower bulbs. Or simply use different voltage bulbs and put a zener across
the lower voltage bulbs to limit what the bulb gets so they dont burn out,
along with a resistor in series with the bulb. Hope you get what im trying
to get at. its late and my thinking is slow right now. have fun.

 

[CFoley1064]

Subject: Re: Hand Crank Generator

From: The Roberto [email protected]
Date: 4/19/2004 6:23 PM Central Standard Time
Message-id: <[email protected]>

It can crank in AC or DC (just a switch of a magnet). I measured it to just a
few
mA and at a plenty fast crank I get out about 12V. Incandescent lamps are
preferred to LEDs and these lamps are the only thing that is going to be
powered.
This project is going to be an exhibit to show kids about energy use and give
them
the idea that it takes a more effort to generate more electricity, so it has
to be
done in some more spectaular way than just a panel meter (just following
orders on
this one, a meter would be fine by me)

I suppose I would want the lights to start turning on at around 4V then 6 and
9.

Thanks,

Roberto

Hi, Roberto. If you're only getting a couple of milliamps, you're not going to
be able to get an incandescent bulb to light up. In fact, you're not going to
get an LED to light, either. Even the "grain o' wheat" incandescent bulbs will
probably bog down your generator. You should be able to run an LM3914 circuit
off a 9V battery, and get results that way. The LM3914 will light up LEDs
based on input voltage. If you set it up for a dot-type instead of a bar-type
display, you should be able to get several hours of life out of a 9V Al Kaline
battery. There are a number of kits available for this IC, which should fill
the bill. Sorry -- I wish I had a better idea for you.

Good luck
Chris

 

[The Roberto]

I should read what I write. I actually get several hundred milliamps. I'm
estimating up to about .5A. It's enough to light up 3 incandescents (1.25V, .3A)
in series adequately

My first attempt at this was to use an array of zener diodes, but the lowest rated
diode would suck up all the current. Someone suggested a current regulating diode,
but the ones that I've found are only rated to about 5V (and a few mA). Is it
worth a shot with these or something similar? Voltage regulating diodes?

Roberto

 

[Seth Koster]

It can crank in AC or DC (just a switch of a magnet). I measured it to just a few
mA and at a plenty fast crank I get out about 12V. Incandescent lamps are
preferred to LEDs and these lamps are the only thing that is going to be powered.

What resistance did you use when measuring your amperage?

 

[Randy Day]

I should read what I write. I actually get several hundred milliamps. I'm
estimating up to about .5A. It's enough to light up 3 incandescents (1.25V, .3A)
in series adequately

My first attempt at this was to use an array of zener diodes, but the lowest rated
diode would suck up all the current. Someone suggested a current regulating diode,
but the ones that I've found are only rated to about 5V (and a few mA). Is it
worth a shot with these or something similar? Voltage regulating diodes?

Just a thought, and *I haven't worked it through*,
but why use the crank to power the lamps at all?

Have a separate power source for the lamps. Just
have the generator create a voltage, so that
when the zener breaks, it turns on a transistor.

I have no values for the resistors, so you'll
have to experiment. MAKE R1 HIGH ENOUGH to limit
the collector current at the max generator
voltage!

R2 biases the transistor off until the zener
breaks.

lamp
.-.
+v -( X )-+
'-' |
|
| R1
\| ___ Zener
|--|___|-+-->|--- to your generator
<| |
| .-.
| | |
GND | |R2
'-'
|
GND

created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

 

[Robert C Monsen]

It can crank in AC or DC (just a switch of a magnet). I measured it to just a few
mA and at a plenty fast crank I get out about 12V. Incandescent lamps are
preferred to LEDs and these lamps are the only thing that is going to be powered.
This project is going to be an exhibit to show kids about energy use and give them
the idea that it takes a more effort to generate more electricity, so it has to be
done in some more spectaular way than just a panel meter (just following orders on
this one, a meter would be fine by me)

I suppose I would want the lights to start turning on at around 4V then 6 and 9.

Thanks,

Roberto

Get zeners of value 3.3V, 5.1V, 8.2V, and 11V.

For each zener, get an NPN power transistor of some kind, and two 1k
resistors. Tie the zener to the input voltage rail on the high side, and to
one of the 1k resistors to the ground. Tie another 1k between the junction
of the 1k and zener, and the base of the NPN. Tie the emitter of the NPN to
ground, and connect up a lamp between the collector and input input voltage.

As the voltage increases, when it gets to Vz + 0.7V, it'll turn on the NPN
transistor, turning on the lamp.

Do this in parallel for each of the zener values, and as the voltage
increases, the lamps will turn on one at a time at voltages 4V, 5.8V, 8.9V,
and 11.7V.

One problem with this circuit is that the current through the lamps will
increase as the voltage goes up. You might theoretically want to limit the
current to some constant value through each lamp, so each lamp has constant
brightness once its turned on. If thats an issue, I can work up a solution
for you.

Regards,
Bob Monsen