wireless signal to activate beeping noise?

[[email protected]]

I'm helping to build a little model for my son's science project. We
want to be able to press a button on a control panel and have a signal
sent wirelessly to a small object. The receiver should be as small as
possible, about the size of a watch battery or smaller, because it has
to fit inside a styrofoam model of a planet. Once this receives this
signal, we want the receiver to make a loud beeping noise.

So basically I need some kind of technology that can send radio (or
radio-esque) signals to a very small receiver, and have that receiver
or something attached to it make a loud beeping noise. The higher the
range of this signal, the better.

Any tips to get me started on this project? I'm an electronics novice
and this project is a long-term one (his science fair is next year) so
I'm perfectly willing to do research on all this if you can point me
in the right direction.

R Gould

 

[[email protected]]

I'm helping to build a little model for my son's science project. We
want to be able to press a button on a control panel and have a signal
sent wirelessly to a small object. The receiver should be as small as
possible, about the size of a watch battery or smaller, because it has
to fit inside a styrofoam model of a planet. Once this receives this
signal, we want the receiver to make a loud beeping noise.

So basically I need some kind of technology that can send radio (or
radio-esque) signals to a very small receiver, and have that receiver
or something attached to it make a loud beeping noise. The higher the
range of this signal, the better.

Any tips to get me started on this project? I'm an electronics novice
and this project is a long-term one (his science fair is next year) so
I'm perfectly willing to do research on all this if you can point me
in the right direction.

R Gould

WIll you have line of sight between transmitted and receiver? If so,
consider using infra-red or ultra-violet LEDs / Transistors for the
signaling. You could even use an old TV remote controller as the
transmitter.

As for a loud noise from a something the size of a watch battery -
that might be pushing things a little too far! Since sound is
effectively the movement of air, you either have to have a large
sounding area, or long travel of the sounding area to produce a loud
noise.

Can you post some dimensions of how big (small) the receiver needs to
be?

 

[[email protected]]

I'm helping to build a little model for my son's science project. We
want to be able to press a button on a control panel and have a signal
sent wirelessly to a small object. The receiver should be as small as
possible, about the size of a watch battery or smaller, because it has
to fit inside a styrofoam model of a planet. Once this receives this
signal, we want the receiver to make a loud beeping noise.

So basically I need some kind of technology that can send radio (or
radio-esque) signals to a very small receiver, and have that receiver
or something attached to it make a loud beeping noise. The higher the
range of this signal, the better.

Any tips to get me started on this project? I'm an electronics novice
and this project is a long-term one (his science fair is next year) so
I'm perfectly willing to do research on all this if you can point me
in the right direction.

R Gould

WIll you have line of sight between transmitted and receiver? If so,
consider using infra-red or ultra-violet LEDs / Transistors for the
signaling. You could even use an old TV remote controller as the
transmitter.

As for a loud noise from a something the size of a watch battery -
that might be pushing things a little too far! Since sound is
effectively the movement of air, you either have to have a large
sounding area, or long travel of the sounding area to produce a loud
noise.

Can you post some dimensions of how big (small) the receiver needs to
be?

 

[[email protected]]

WIll you have line of sight between transmitted and receiver? If so,
consider using infra-red or ultra-violet LEDs / Transistors for the
signaling. You could even use an old TV remote controller as the
transmitter.

As for a loud noise from a something the size of a watch battery -
that might be pushing things a little too far! Since sound is
effectively the movement of air, you either have to have a large
sounding area, or long travel of the sounding area to produce a loud
noise.

Can you post some dimensions of how big (small) the receiver needs to
be?

Kenny, thanks for your response.

There will be no line of sight between the sender and receiver. In
fact, one of the major needs for this is that it can be accomplished
without seeing the receiver at all.

When I imagine the size of the receiver, I am thinking of something
about the size of a standard watch battery, or a quarter. Or let's
say something smaller than the head of an average house key.

As for making the sound, that's a good point you bring up. I hadn't
considered that. I had a small device that could make a sound up to
110 db, but then again that device was still quite a lot bigger than
my imagined receiver. How loud a sound do you think I could make with
a device the size of a watch battery?

R gould

 

[D from BC]

Kenny, thanks for your response.

There will be no line of sight between the sender and receiver. In
fact, one of the major needs for this is that it can be accomplished
without seeing the receiver at all.

When I imagine the size of the receiver, I am thinking of something
about the size of a standard watch battery, or a quarter. Or let's
say something smaller than the head of an average house key.

As for making the sound, that's a good point you bring up. I hadn't
considered that. I had a small device that could make a sound up to
110 db, but then again that device was still quite a lot bigger than
my imagined receiver. How loud a sound do you think I could make with
a device the size of a watch battery?

R gould

A beeper the size of a watch battery....geezz
I expect no louder than your average beeping digital watch....

For all I know, a firecracker exploding (size of a watch battery) is
still not loud enough.


D from BC

 

[Paul Hovnanian P.E.]

Kenny, thanks for your response.

There will be no line of sight between the sender and receiver. In
fact, one of the major needs for this is that it can be accomplished
without seeing the receiver at all.

When I imagine the size of the receiver, I am thinking of something
about the size of a standard watch battery, or a quarter. Or let's
say something smaller than the head of an average house key.

As for making the sound, that's a good point you bring up. I hadn't
considered that. I had a small device that could make a sound up to
110 db, but then again that device was still quite a lot bigger than
my imagined receiver. How loud a sound do you think I could make with
a device the size of a watch battery?

For how long? I have a piezo alarm that produces about 100-110 dB from
two watch batteries. But not for long (maybe 10-15 minutes). Its bigger
than what you describe, but most of this is due to the size of the piezo
transducer.

 

[[email protected]]

For how long? I have a piezo alarm that produces about 100-110 dB from
two watch batteries. But not for long (maybe 10-15 minutes). Its bigger
than what you describe, but most of this is due to the size of the piezo
transducer.

Do you mean that it will only be useable for 15 minutes before it is
dead?

Also, I wouldn't actually need it to be 100 db... half of that would
suffice, I think (I'd have to test that.)

gould

 

[Tim Williams]

As for making the sound, that's a good point you bring up. I hadn't
considered that. I had a small device that could make a sound up to
110 db, but then again that device was still quite a lot bigger than
my imagined receiver. How loud a sound do you think I could make with
a device the size of a watch battery?

Put a cicada inside it.

How you activate it is your problem. :^)

Tim

 

[Ken S. Tucker]

Kenny, thanks for your response.

There will be no line of sight between the sender and receiver. In
fact, one of the major needs for this is that it can be accomplished
without seeing the receiver at all.

When I imagine the size of the receiver, I am thinking of something
about the size of a standard watch battery, or a quarter. Or let's
say something smaller than the head of an average house key.

Is an antenna size considered?
Ken

 

[Bob]

Do you mean that it will only be useable for 15 minutes before it is
dead?

Also, I wouldn't actually need it to be 100 db... half of that would
suffice, I think (I'd have to test that.)

gould

Human hearing is logarithmic. Half the power is 97dB.
Half the decibel level, 50dB is around the level of the fan in
my computer at 1meter and the sound level in my garden
with a few cars doing 30mph a couple of hundred meters
away. 50dB at 1m will only be noticed by people close by
if it goes off in a big room with people moving around or
talking.

Ken's question about antenna size is an important consideration,
would a 6inch diameter loop be possible?
I assume you are in the USA, do you care about FCC rules?
Nobody will notice a few ocasionally strong transmissions.

Battery size is going to be an issue.

One idea is to use a 4watt CB radio transmitter to get a strong
signal.
A small loop antenna, tuned to resonance at 27MHz with a capacitor
would pick up enough signal to turn on a transistor that completes
a circuit to allow current from a couple of watch batterys to flow
through
a buzzer. Almost zero power use when inactive.
A loop antenna is polarised so you might want to use to two
perpendicular to each other.

If you want to use a low power transmitter you will have to use a
sophisticated receiver. Given the constraints you will have to
buy an off the shelf module.

Bob



Bob

 

[HapticZ]

I'm helping to build a little model for my son's science project. We
want to be able to press a button on a control panel and have a signal
sent wirelessly to a small object. The receiver should be as small as
possible, about the size of a watch battery or smaller, because it has
to fit inside a styrofoam model of a planet. Once this receives this
signal, we want the receiver to make a loud beeping noise.

So basically I need some kind of technology that can send radio (or
radio-esque) signals to a very small receiver, and have that receiver
or something attached to it make a loud beeping noise. The higher the
range of this signal, the better.

Any tips to get me started on this project? I'm an electronics novice
and this project is a long-term one (his science fair is next year) so
I'm perfectly willing to do research on all this if you can point me
in the right direction.

R Gould

use the 'planet' as a form for the antennae loop, that will get you the
maximum diameter for effective signal pickup

tune it to some off beat freq nobody uses,

create a transmitter to just emanate some same freq signal to force the
tuned circuit into resonance

you dont need too much distance i hope

use the tuned osscillations to somehow trigger a closure (field effect
xistor switch?) of battery power to a piezo buzzer

the buzzer could be made the same diameteras the sphere to also maximize the
decibel output

 

[T]

I'm helping to build a little model for my son's science project. We
want to be able to press a button on a control panel and have a signal
sent wirelessly to a small object. The receiver should be as small as
possible, about the size of a watch battery or smaller, because it has
to fit inside a styrofoam model of a planet. Once this receives this
signal, we want the receiver to make a loud beeping noise.

So basically I need some kind of technology that can send radio (or
radio-esque) signals to a very small receiver, and have that receiver
or something attached to it make a loud beeping noise. The higher the
range of this signal, the better.

Any tips to get me started on this project? I'm an electronics novice
and this project is a long-term one (his science fair is next year) so
I'm perfectly willing to do research on all this if you can point me
in the right direction.

R Gould

Check here:
http://www.sparkfun.com/commerce/categories.php?cPath=16_79

I've got this one:
http://www.sparkfun.com/commerce/product_info.php?products_id=872


I use it to get two Arduino boards talking to each other. They're good
up to 150m which is a fair distance and the one I've got operates on
434MHz.

 

[Paul Hovnanian P.E.]

Do you mean that it will only be useable for 15 minutes before it is
dead?

Producing noise, yes. The batteries can power the alarm in a passive
state for many months.