My son wants to enter the 4th grade science fair and wants to do
something with electronics. As with most science fairs, the primary
point is to "solve a problem" or prove a theory. I have millions if
ideas for him, but can't seem to settle on any particular one. He's
limited to certain power sources. He can only use batteries totaling
up to six volts. Nothing in the exhibit can be plugged in, even test
equipment. I was going to let him use my oscilloscope to demonstrate
how a transistor amplifies, until I read about the power restrictions.
Does anybody have any ideas for a simple project that doesn't require
a whole lot of explanation to a ten year old? He'll need to understand
the basic theory himself, which I'm able to coach him on, and be able
to answer teacher's questions about it. I also would like it to be
somewhat impressive. For example, I don't want a project like "How
does a resister work".


.......... I just thought of an idea while typing this that may be
intriguing. I'll still like to hear any opinions or ideas from others
on different suggested projects. The thought I came up with would be a
demonstration on skin resistance. Using maybe a transistor amplifier
and/or oscillator, a person could press two fingers from the same hand
on two metal contacts and demonstrate that through surface contact and/
or varying moisture on the skin can change the frequency of the
oscillator. The oscillator can be heard in a speaker. I guess I'm
talking about a biofeedback monitor of sorts.

Any ideas?

Thanks,
Jeff

<jsalzman@gmail.com> wrote in message
news:669b2b90-20ad-445d-8664-0a1dba6650cd@a1g2000hsb.googlegroups.com...
> My son wants to enter the 4th grade science fair and wants to do
> something with electronics. As with most science fairs, the primary
> point is to "solve a problem" or prove a theory. I have millions if
> ideas for him, but can't seem to settle on any particular one. He's
> limited to certain power sources. He can only use batteries totaling
> up to six volts. Nothing in the exhibit can be plugged in, even test
> equipment. I was going to let him use my oscilloscope to demonstrate
> how a transistor amplifies, until I read about the power restrictions.
> Does anybody have any ideas for a simple project that doesn't require
> a whole lot of explanation to a ten year old? He'll need to understand
> the basic theory himself, which I'm able to coach him on, and be able
> to answer teacher's questions about it. I also would like it to be
> somewhat impressive. For example, I don't want a project like "How
> does a resister work".
>
>
> ......... I just thought of an idea while typing this that may be
> intriguing. I'll still like to hear any opinions or ideas from others
> on different suggested projects. The thought I came up with would be a
> demonstration on skin resistance. Using maybe a transistor amplifier
> and/or oscillator, a person could press two fingers from the same hand
> on two metal contacts and demonstrate that through surface contact and/
> or varying moisture on the skin can change the frequency of the
> oscillator. The oscillator can be heard in a speaker. I guess I'm
> talking about a biofeedback monitor of sorts.
>
> Any ideas?
>
> Thanks,
> Jeff


You can build a cute little DC motor from a wire loop. The users connect it
up, and the motor spins. Very easy, and all it costs is enamel wire, a
magnet, and the battery.

It has been done enough so there are easy instructions all over the place.
Look here:

http://www.sciencebuddies.org/science-f ... p009.shtml

Regards,
Bob Monsen

jsalzman@ gmail.com wrote:
>[...]For example, I don't want a project like "How does a resister work".
> Jeff
>
If there's anything to genetics, you should have him use a
spellchecker
before applying a magic marker to any signage.

>[...]The thought I came up with
>would be a demonstration on skin resistance.
>
....and you could mention that the "Passion Meters" in arcades
and the "E-Meter" used by a certain pseudo-religion are cheap parlor
tricks.

"Bob Monsen" <rcmonsen@gmail.com> wrote in message
news:zUcCj.954$LV5.116@newssvr19.news.prodigy.net...
> <jsalzman@gmail.com> wrote in message
>> He can only use batteries totaling
>> up to six volts.

I like the idea of providing that restricting power sources by voltage is
rather pointless since it doesn't really restrict anything important such as
power or energy storage. To demonstrate this I'd have him build a boost power
supply... the higher the voltage, the better. A Jacob's ladder could be
fun, and something like a 6V trolling motor battery would have plenty of power
to keep it going for some hours.

I'm being a little facetious here, but realistically with something like an
ignition coil or neon lamp transformer and a simple vibrator-based inverter
you probably could build a small Jacob's ladder simply enough that a
10-year-old would have a shot at understanding it pretty thoroughly.

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jsalzman@gmail.com wrote:
> Any ideas?

How about a infra red / laser phone - you have a modulated light source
as the transmitter and a photodiode or LDR as the receiver. You can
modulate using a transformer, transistor, opamp, etc.

There are a ton of circuits out there for that sortof thing.

- --
Brendan Gillatt | GPG Key: 0xBF6A0D94
brendan {a} brendangillatt (dot) co (dot) uk
http://www.brendangillatt.co.uk
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On Mar 13, 4:39 am, jsalz...@gmail.com wrote:
> My son wants to enter the 4th grade science fair and wants to do
> something with electronics. As with most science fairs, the primary
> point is to "solve a problem" or prove a theory. I have millions if
> ideas for him, but can't seem to settle on any particular one. He's
> limited to certain power sources. He can only use batteries totaling
> up to six volts. Nothing in the exhibit can be plugged in, even test
> equipment. I was going to let him use my oscilloscope to demonstrate
> how a transistor amplifies, until I read about the power restrictions.
> Does anybody have any ideas for a simple project that doesn't require
> a whole lot of explanation to a ten year old? He'll need to understand
> the basic theory himself, which I'm able to coach him on, and be able
> to answer teacher's questions about it. I also would like it to be
> somewhat impressive. For example, I don't want a project like "How
> does a resister work".
>
> ......... I just thought of an idea while typing this that may be
> intriguing. I'll still like to hear any opinions or ideas from others
> on different suggested projects. The thought I came up with would be a
> demonstration on skin resistance. Using maybe a transistor amplifier
> and/or oscillator, a person could press two fingers from the same hand
> on two metal contacts and demonstrate that through surface contact and/
> or varying moisture on the skin can change the frequency of the
> oscillator. The oscillator can be heard in a speaker. I guess I'm
> talking about a biofeedback monitor of sorts.
>
> Any ideas?
>
> Thanks,
> Jeff


Fun with the 555?

MD

These are some pretty good ideas. These are certainly some ideas that
I haven't thought of.

Thanks,
Jeff