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BryanJ
Posted on Tuesday, May 20, 2003 - 5:34 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I was wondering if I could build the transmitter with an oscillator that is larger than 1Mhz; something like a 5Mhz, and how many miles would you saw that it would sent if it had a 25 foot antenna. Also, where would I find a 5Mhz oscillator that would work for the project (for a reasonable price)?
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Simon Quellen Field (Sfield)
Posted on Tuesday, May 20, 2003 - 6:26 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

One megahertz is the frequency, not the power.
Raising the frequency would not increase the range.

We selected 1 Mhz because it can be received on a
cheap AM radio. If you used a higher frequency, such
as 5 Mhz (which is in the 60 meter short wave band),
you would need a short wave radio to receive it.

When I sent messages from San Diego to Texas using one
of these, I selected 28.322 Mhz for several reasons.
First, it is a common frequency, so off-the-shelf oscillators
are not difficult to come by. Second, it is a legal
frequency to use if you have an entry-level Amateur Radio
license, so I would maximize the number of people who
might be able to talk back to me. Third, it is in the
10 meter band, so the E layer of the ionosphere can reflect
it. This means that I can bounce the signal off of the
ionosphere, and thus reach the other side of the world.

The drawback was that the receiver for the 10 meter band
is more expensive than the $5 AM radio you can use with
1 Mhz.

The little transmitter is legal to use in the AM band because
it puts out so little power. If you wish to send the signal
farther, it is really easy to get an amateur radio license
(a few dollars and a simple written test you can practice on
the Internet -- all of the questions and the answers are
published, so you can just memorize them if you want). With
a license, you can use bigger antennas, you can use higher
power transmitters, and you can use many frequencies that
can go around the world.
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Anonymous
Posted on Thursday, June 5, 2003 - 8:24 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

But how to increase the range? I want to send messages only inside a city.
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Simon Quellen Field (Sfield)
Posted on Thursday, June 5, 2003 - 1:56 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

You need a license to transmit city-wide.
Go to the ARRL website to get a license.
Then you can use 28.322 Mhz and an easily obtained amplifier.
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Anonymous
Posted on Friday, June 6, 2003 - 1:05 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I live in Viet Nam so i think if i transmit something in 1Mhz, no one can know... So, why we have to use 28.322 Mhz, why is not 1Mhz? And is it cheap to do it?
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Simon Quellen Field (Sfield)
Posted on Friday, June 6, 2003 - 6:51 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

The reason for choosing 1 Mhz was that there are very cheap
radios that can receive that frequency. If you have such radios
where you live, then it is likely that the AM band is being used
by people who would object if you put out a strong signal that
interfered with them. Governments usually protect and regulate
the airwaves, and license certain frequencies for amateur use.

Using frequencies other than those you are allowed to use can
get you into trouble, unless the power is so low that it is effectively
limited to your own house, and thus will not interfere with anyone else.

That is why our design is legal, even though the frequency is normally
used by radio stations.

The 10 meter band (in which 28.322 Mhz resides) is governed by international
treaty, and so I know that you can get a license to use that frequency
with power high enough to cover the entire globe, and extend into outer
space.
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Anonymous
Posted on Saturday, June 7, 2003 - 4:30 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

How much a 28.322 Mhz AM radio tranmitter?
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Simon Quellen Field (Sfield)
Posted on Saturday, June 7, 2003 - 2:32 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Ok people -- how many of you want 28.322 Mhz oscillators
but are finding them difficult to find? Should I offer
them in our catalog? I can probably have them made for
the same price as the 1 Mhz oscillators.

How many readers have amateur radio licenses?
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Anonymous
Posted on Tuesday, September 2, 2003 - 4:30 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I BUILT A COMPUTER CONTROLLED TRANSMITTER BUT IT WONT WORK I CHECKED EVERYTHING BUT IT WONT DO ANYTHING THE LED WONT LIGHT UP OR ANYTHING THE PORT DOESE WORK CAUSE IT USED TO HAVE A INFRARED MOUSE SO WHAT COULD THE PROBLEM BE?

BY THE WAY HOW FAR WILL A 53.2659MHZ OSCILLATOR TRANSMIT?
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Simon Quellen Field (Sfield)
Posted on Tuesday, September 2, 2003 - 6:31 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

It sounds like you are using the wrong port.
The software lets you select which port to use.
Try another port.

It is also possible that you have made a mistake
in the construction, such as a short circuit or a
solder bridge. Check everything over carefully.

An oscillator for 53 Mhz will be limited to line-of-sight
operation except under unusual circumstances.
That frequency does not skip off of the ionosphere
like 28 Mhz does.
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Anonymous
Posted on Thursday, September 4, 2003 - 2:02 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

so...what port should i use? my computer only has one port that is a male connector in that the transmitter fits on.
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Simon Quellen Field (Sfield)
Posted on Thursday, September 4, 2003 - 3:23 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

On a PC, the ports are called COM1:, COM2:, COM3:, etc.
Find out which port the infrared mouse was using.
That will be the port associated with the connector
to which you have attached the transmitter.

You might also be having trouble if the software for
the infrared mouse is still active, and still controlling
that port. You might want to disable the infrared mouse
software while using the port for other hardware.
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Anonymous
Posted on Thursday, September 4, 2003 - 10:50 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

how do i disable the infrared mouse?
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Simon Quellen Field (Sfield)
Posted on Thursday, September 4, 2003 - 11:41 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

You will have to read the manual, or contact the manufacturer.
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Anonymous
Posted on Saturday, September 6, 2003 - 12:25 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

i got the transmitter to work and i also downloaded the cwget program to decode the signals. were do i conncet the am radio? do i connect it the microphone or the input in jack. also is the sound in input jack stereo or mono so i can get a suitable cable to connect it in
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Simon Quellen Field (Sfield)
Posted on Saturday, September 6, 2003 - 2:00 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

You can try each of the inputs (microphone or line-in) to see
which works best for you. A mono plug will work in a stereo jack,
so you can use either mono or stereo as you choose.
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Anonymous
Posted on Saturday, November 8, 2003 - 12:39 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I foud an oscillator that is 1843.200KHz. How much is this in MHz and could this oscillator work for transmitting and what kind of receiver would be needed.
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Simon Quellen Field (Sfield)
Posted on Saturday, November 8, 2003 - 3:39 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

The prefix "kilo" means "thousand".
The prefix "mega" means "million".
Thus, you have a 1.8432 Megahertz oscillator.

This frequency is in the middle of the 160 meter
Amateur Radio band. You need a General Class license
to transmit in this band. The General class requires
one extra test beyond the entry level test needed for
being a licenced radio amateur. That said, the test
is still pretty easy (my daughter got her General Class
license when she was 15, and I'm sure there are kids
younger than 6 who have General Class licenses).

Since normal AM radios only go up to 1.7 Mhz, you will
want a shortwave radio to receive at this frequency.
If you look up "simple shortwave receiver" in Google,
you will find many simple circuits you can build.
Or, you can modify our Three Penny Radio" for shortwave
reception by adding a capacitor in series with the
tuning capacitor, to raise the frequency. The added
capacitor can be another variable capacitor from our
catalog.
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Anonymous
Posted on Wednesday, March 31, 2004 - 2:01 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I would like to know if, in the computer-controlled transmitter project, a JENRA 49.860 MHz oscillator can be used without a license.
(P.S. It was found in a toy walkie-talkie)
Also, would a 9 position male D-Sub connector work instead?
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Simon Quellen Field (Sfield)
Posted on Wednesday, March 31, 2004 - 5:08 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

First of all, the part labelled "49.860" is most likely a crystal,
not an oscillator. An oscillator will have more than two leads.

Next, as long as you don't interfere with other communications, and
are willing to accept interference with your own communications, you
are generally protected under Part 15 of the FCC regulations, although
you should read those regulations yourself to be aware of the limitations.
See the FCC web site (go to "http://www.fcc.gov" and search for "part 15").

I would be surprised if your computer had a connector of the wrong gender.
Trying to plug a male into a male will not work.
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mei
Posted on Monday, April 19, 2004 - 7:57 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

is it possible to encode what one transmits, so as to only have one's friends to communicate with?
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Simon Quellen Field (Sfield)
Posted on Monday, April 19, 2004 - 8:29 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Certainly.
You can use any of the common encryption schemes, or you
can invent your own.

Suppose you scramble the alphabet and write the result as a word
on a piece of paper. Then do it again, and write the new word
on the next line, and so on until the paper is full.

Now make a copy of the paper, and give your friend the copy.
No one else in the world has this series of scrambled alphabets.

Now, whenever you need to send an 'A', send the first letter of
the first line on the paper. Then cross out that line, so you never
use it again. If the next letter is a 'D', count over 4 letters on the
second line, and send that letter. Then cross out that line.
Keep doing this until you have sent your entire message.

Your friend receives the first letter, and decodes it by noticing that it
is the first letter on his decoding page, so it must be 'A'. He continues
to decode this way, until he has the whole message.

Because you are crossing out the lines and never using them again,
no one can decode your message but you and your friend.

You can do all of the tedious parts by writing a computer program.
You can exchange your decoding pages (called "one time pads") by
carrying the file by hand or mailing it to your friend. You can make
years worth of them and still fit it all in a small file.
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mei
Posted on Wednesday, April 21, 2004 - 6:26 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

how can one encode the signal being emitted from the transmitter so as to only have friends able to listen?...OR is it even possible to--speak into a mic-- have the sound signal scrambled(or radio signal), sent out and have a friend recieve(a somehow descrambled signal or sound wave)a meaningful conversation, as oppossed to meaningless noise?
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Simon Quellen Field (Sfield)
Posted on Thursday, April 22, 2004 - 12:03 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

The previous message contained a long description of how to do that,
in answer to your first question.

All of the methods within your budget use computers to do the tedious
parts. Look up "PGP encryption" on Google to find free programs to do
it. Record your voice using a sound card. Encrypt the sound file with
PGP. Send the encrypted data over the radio link as dots and dashes.
Your friend will receive those, convert them to a computer file, run the
PGP decryption program on the file, and listen to it.

There are other ways, but I think you will find most of them difficult to
realize, or too expensive. Look up "scrambling circuit" on Google.
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Anonymous
Posted on Sunday, October 3, 2004 - 6:25 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

A few questions.
1. I have two 9-pin ports label "IOIOIO A" and "IOIOIO B"; which one do I use and which port (COM 1 or COM 2) is it?

2. I tried putting them into the ports anyway and the LED just went on solid without me sending any message with the Transmitter Program. What should I do?

3. I was using the command line version of the transmitter program and when I started it up, the first line said " Can't open 'com1:' " What should I do?
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Simon Quellen Field (Sfield)
Posted on Tuesday, October 5, 2004 - 5:24 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

The manual for your computer should tell you which port is
com1 and which is com2. If you don't have a manual, you can
probably find one on the web.

It should be easy to tell which is which, however. Attach a
serial device (such as a modem) to a port and see if you can talk
to it as com1 or com2, using a terminal program such as HyperTerminal.

When you do determine which port to use, and the program is running,
the LED will flash. It is OK if the LED is on solidly before the
program is running.

When you have the transmitter connected to com1, the program should
stop telling you that it can't open com1.
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max
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Posted on Thursday, December 16, 2004 - 11:28 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

A got a few questions:
Where can I buy a 1.000 Mhz oscillator besides in your catalog? If radio shack sells them, do you know the product number?

What is the radio shack number for a 14 pin socket, and what is the radio shack number for a general purpose circuit board?

Also, can you give me very specific step-by-step instruction for making an antenna? Could you tell me how, and not just tell me to use the antenna book you suggested before in one of my previous posts? Thanks!

P.S. Is the oscillator in the computer controlled transmitter the same one reffered to in the "AM transmitter from simple parts"? Thnx again!

P.P.S Have you written any other books besides "Gonzo Gizmos"?
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Simon Quellen Field (sfield)
New member
Username: sfield

Post Number: 32
Registered: 12-2004
Posted on Friday, December 17, 2004 - 12:17 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I don't think Radio Shack sells oscillators.
You might try another electronics part retailer.

You can look up Radio Shack part numbers on
their web site. They have a search box where you
can type in what you are looking for.

The antenna does not need to be outside, but the
bigger it is the better it will work.

I have already discussed how to attach the test lead to
the wire leading up to a rooftop antenna. It's that simple.

The oscillator in both projects is the same one.
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David L. Rice
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Posted on Monday, January 24, 2005 - 6:38 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Hi! My son is using your circuits for a science project and I built one first to make sure it would work for him. It seems ideal since he has very limited soldering experience. I have been able to make the cw mode of the xmit program work very well, but when I attempt to use the hig and low tone modes I receive something that sounds like 60 cycle buzz. I'm certain my the computer I'm using is fast enough to perform the functions of turning on and off the com port. .what am I missing here? ( I have used both a 25 mhz and a 1.6 mhz oscillator.
Thanks in advance for any solutions you may have.
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Simon Quellen Field (sfield)
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Username: sfield

Post Number: 159
Registered: 12-2004
Posted on Monday, January 24, 2005 - 7:39 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

You could verify the frequencies with an oscilloscope,
but the buzz should be all you need.
The idea is to amplitude modulate the signal, so
a cheap AM radio can receive it.
It sounds like you are there.
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Anonymous
 
Posted on Thursday, January 27, 2005 - 6:40 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

i am ready with all my hardware parts +.but i am not getting the programme required to transmitt and receive the messages. could you please help me?
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sandip puraneindia
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Posted on Thursday, January 27, 2005 - 6:43 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

i am ready with all my hardware parts +.but i am not getting the programme required to transmitt and receive the messages. could you please help me?
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Simon Quellen Field (sfield)
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Username: sfield

Post Number: 164
Registered: 12-2004
Posted on Thursday, January 27, 2005 - 10:41 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

You will have to provide more information about
your problem.

Are you having difficulty downloading the program?
If you have downloaded it, are you having trouble running it?
If you are running it, are you having trouble
determining if it is powering the oscillator?
Have you checked that your serial port works by
using HyperTerm (built-in to Windows)?
Are you sure you have connected to the right
serial port?

An inexpensive tool like this serial line tester or this cheaper one
will help, although you might want to find a
9 pin version, or use a 9 pin to 25 pin adapter.
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Anonymous
 
Posted on Sunday, March 20, 2005 - 8:57 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

The C++ Program Doesnt Work!!!

There is a compile errpr
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JasonDalton
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Posted on Wednesday, March 23, 2005 - 11:53 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Hi Simon,

I enjoyed your article in Make magazine. What a great mag for people who like tinkering with stuff. Why did you take the computer controlled radio off your site? are you moving things off that will get put into Make or another publication?

Thanks for your help BTW earlier, everything worked out great eventually.
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JasonDalton
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Posted on Wednesday, March 23, 2005 - 11:55 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Silly me, i didn't notice you had created a new section. Way to go simon!
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Kushal
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Posted on Thursday, May 5, 2005 - 5:45 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

i got a 48 mhz oscillator does it will work for the project of computer controlled transmitter.
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Simon Quellen Field (sfield)
Senior Member
Username: sfield

Post Number: 372
Registered: 12-2004
Posted on Thursday, May 5, 2005 - 10:51 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

You will need a receiver that is capable of receiving AM signals at 48 Mhz.
That may be hard to find.

We sell the 1 Mhz oscillator in our catalog because cheap AM radios
can receive the signal easily.
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kushal
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Posted on Friday, May 6, 2005 - 1:42 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

thanks for telling me
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Jonathan Blissett
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Posted on Thursday, May 19, 2005 - 2:19 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Hello,
Please could you tell me if a 100mhz oscillator work for the computer controlled radio transmitter project.
Thankyou
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Simon Quellen Field (Sfield)
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Username: Sfield

Post Number: 421
Registered: 12-2004
Posted on Thursday, May 19, 2005 - 2:48 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

It is highly unlikely that you will find a receiver that can
receive AM signals in the middle of the FM band.
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kushal
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Posted on Sunday, May 22, 2005 - 4:38 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

hi simon am kushal i am from india i got the 28.322 mhz oscillator but can i get morse code on normal radio it has three mode MW FM and SW or will i need to buy that expensive short wave radio. and tell me how to built that 28.322 mhz computer controlled transmitter with full information .and tell me what other things wil be needed .
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sfield
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Posted on Sunday, May 22, 2005 - 12:45 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

The traqnsmitter is the same no matter which frequency your
oscillator uses.

If your receiver can tune to that frequency, then try it once
you get your license. There are many shortwave bands, and not
all cheap shortwave recievers can receive all the way up in the
10 meter band (28.322 Mhz). Try the 1 Mhz version first.
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kushal
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Posted on Sunday, May 22, 2005 - 1:08 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

yes i have license and i did the 1 mhz version i got sucess. but in of my radio is of philips company and and it has seletion in shortwave from 60 meter band to 19 meter band is this the problem for which i am not able to get morse code from 28.322 mhz oscillator . and which radio should i use.
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Simon Quellen Field (Sfield)
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Post Number: 432
Registered: 12-2004
Posted on Sunday, May 22, 2005 - 1:21 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

The Ramsey FR10C should work fine.

My ICOM will do a better job though.
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kushal
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Posted on Sunday, May 22, 2005 - 1:27 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

in this ramsey fr10c i wil get 10 m band
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Simon Quellen Field (Sfield)
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Username: Sfield

Post Number: 433
Registered: 12-2004
Posted on Sunday, May 22, 2005 - 1:29 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

That's why it is called the FR10C.

But go for the ICOM -- you'll like it much better.
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kushal
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Posted on Sunday, May 22, 2005 - 1:36 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

but what is the cost of icom
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Simon Quellen Field (Sfield)
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Post Number: 434
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Posted on Sunday, May 22, 2005 - 2:12 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

$10,499.00 as of this writing.
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Norman A Alcantara (Glvertex_nhor)
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Posted on Wednesday, May 25, 2005 - 1:05 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Simon Quellen Field:

I am wondering how the Transmitter discussed in Scitoys can send a text messages.because the tutorial did not mentioned anything about sending a text messages. How can I send a Text Messages to my cellphone using the simple transmitter?

Norman
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Simon Quellen Field (Sfield)
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Post Number: 440
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Posted on Wednesday, May 25, 2005 - 2:03 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

You have a cell phone that understands Morse Code?
And listens to the AM broadcast band at 1 Mhz?
I've never seen one of those.

Our transmitter sends messages in Morse Code to a receiver
connected to another computer. You type your text message
into our program, and it gets transmitted to the receiver,
and decoded by the receiver's computer, showing up as text
on that computer's screen.

No cell phone is needed.
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Norman A Alcantara (Glvertex_nhor)
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Posted on Wednesday, May 25, 2005 - 9:59 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

No, I dont a have a cellphone like that. That is the reason why Im wondering about it. Ok now I understand transmitter to transmitter via a computer I thought I can used this to send a text message to a cellphone device. Ok It means that if I build 3 transmitter, and those 3 are online and I will try to send a Text messages,So the other 2 transmitters can received my messages? It is possible to control the transmittion, like for example only one transmitter can only receive my messages?

norman
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Simon Quellen Field (Sfield)
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Post Number: 441
Registered: 12-2004
Posted on Wednesday, May 25, 2005 - 10:39 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Just so there is no confusion:
Transmitters transmit.
Receivers receive.

Radios are said to be "on the air", not "online".
You control who receives radio signals by changing the frequency.
Each transmitter would transmit on a different frequency, and
in this way each receiver can be tuned to the frequency of the transmitter
they wish to listen to. This is why receivers have little round knobs
that can adjust the frequency they receive.

If you don't want anyone but your friends to understand what you are
sending, you use a thing called a code, where you agree on different
meanings for words. For example, to prevent the enemy from knowing
that they were working on armored vehicles, the army used the word "tank"
so that people would think they were building water tanks. The code
word eventually made it into the language, and we call armored vehicles
"tanks" to this day.
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Norman A Alcantara (Glvertex_nhor)
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Posted on Thursday, May 26, 2005 - 12:03 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I see your point, now I understand. But Im having trouble understanding your program Because it is written in C++ im using VB and Java language are there any available Program written in VB or Java to transmitt a Message? and my second problem is how far can a 1.00 Mhz Oscillator can reach? and if i will try to extend more my Antena is there any possibility to further more my nerwork?
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Simon Quellen Field (Sfield)
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Username: Sfield

Post Number: 442
Registered: 12-2004
Posted on Thursday, May 26, 2005 - 10:08 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

C++ is not difficult to learn, especially if you already know a
couple other languages. Having another tool under your belt is
a good thing.

We share the airwaves. If everyone was sending radio signals at
1.0 Mhz over long distances, no one would be able to communicate.
To prevent that, the law and international treaties limit the amount
of power you can use without a license. This means that for any
serious application where you want good signal to noise ratios over
any reasonable distance, you will want to get a license.

The good news is that it is very easy to get a license.
Go to the ARRL web site to learn how.
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Norman A Alcantara (Glvertex_nhor)
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Username: Glvertex_nhor

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Posted on Thursday, May 26, 2005 - 11:15 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Ok I will study C++, My last question before I proceed building my own transmitter. What if incase that there are two persons trying to transmitt a Text Message in a transmitter what will happen to their messages after receiving it? for example Person A is sending "Hello" and Person B is sending "Bye Bye" at the same time. And received their message like this "Bye Hello Bye" or "He Byello Bye" etc. What do you think?

Norman
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Simon Quellen Field (Sfield)
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Username: Sfield

Post Number: 443
Registered: 12-2004
Posted on Thursday, May 26, 2005 - 12:21 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

If two transmitters are sending different messages but on the same
frequency using AM, you will hear both at the same time, like two
people talking to you at the same time. In FM, you will only hear
the strongest signal.

With two people talking at once on the same frequency, the Morse Code
decoder will have a difficult time figuring out what is being said,
just as you would. That kind of interference is called QRM.
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Norman A Alcantara (Glvertex_nhor)
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Posted on Thursday, May 26, 2005 - 10:02 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I see, So there is any solutions to Solve QRM? or To control QRM and retrive the message as is like what they sent? And How can i switch my Transmitter/Transceiver From AM to FM? Thanks a lot.

norman
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Simon Quellen Field (Sfield)
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Post Number: 447
Registered: 12-2004
Posted on Friday, May 27, 2005 - 11:11 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

You solve interference by moving to a different frequency.

Changing from AM to FM is like changing a bicycle into a submarine.
You basically start over, and build an FM transmitter.
There are lots of circuits on the web, Google for "simple fm transmitter".
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Norman A Alcantara (Glvertex_nhor)
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Username: Glvertex_nhor

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Posted on Saturday, May 28, 2005 - 12:20 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Ok thanks for ur help Simon, How long it will take to receive your products here in the Phillipines? 2 to 3 days?

(Message edited by Glvertex_nhor on May 27, 2005)
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Simon Quellen Field (Sfield)
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Post Number: 451
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Posted on Saturday, May 28, 2005 - 3:25 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

That's the time it takes for U.S. shipments.
I would expect longer for the Phillipines.
Let us know.
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Anonymous
 
Posted on Sunday, June 26, 2005 - 4:11 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Simon,
You say that the oscillator for the am transmitter is like the ones from a computer. Are there oscillators off of a computer that I could use to make my transmitter or would it not be the right frequency? Thanks
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Simon Quellen Field (Sfield)
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Post Number: 515
Registered: 12-2004
Posted on Sunday, June 26, 2005 - 4:38 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Modern computers use oscillators that are thousands of times
higher in frequency than 1 Mhz. It is unlikely that you will
find an oscillator in consumer electronics equipment that will
be in the AM band. But brand new oscillators are not that expensive.
See our catalog.
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Anonymous
 
Posted on Monday, June 27, 2005 - 1:14 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Thanks I will probably place an order soon.
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erin r erikson (Freakydoo)
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Posted on Friday, July 22, 2005 - 6:46 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

can this system be used to control a radio controlled car? which programs might work best?
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Simon Quellen Field (Sfield)
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Post Number: 588
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Posted on Friday, July 22, 2005 - 6:53 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

If you want to have your computer control the car it's even easier
than the transmitter project.

Just use a CMOS switch like the 4066.
Use the computer's parallel port to control it.
Replace the switches in the remote control with the 4066.
Use a simple BASIC program to send bits to the parallel port.
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erin r erikson (Freakydoo)
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Posted on Friday, July 22, 2005 - 7:05 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

cool quick response. but forgive my ignorance do you know where I could find a visual represention of the proccess you just explained.
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erin r erikson (Freakydoo)
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Posted on Friday, July 22, 2005 - 7:22 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

ok i wasn't sure what the cmos switch was but i looked at a picture so i'm good with that. but i'm still lost on the proccess.
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priya
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Posted on Wednesday, August 31, 2005 - 2:36 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I want to modify a radio that can communicate to a nearby place (ex. to get information from a nearby located place were the database is stored)without towers, for which i would like to use FM trasnmission.Can i know if it`s possible & how I`m a final ComputerScience student(B.E).
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priya
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Posted on Wednesday, August 31, 2005 - 2:51 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I want to modify a radio that can communicate to a nearby place (ex. to get information from a nearby located place were the database is stored)without towers, for which i would like to use FM trasnmission.Can i know if it`s possible & how I`m a final ComputerScience student(B.E).
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Simon Quellen Field (Sfield)
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Post Number: 653
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Posted on Wednesday, August 31, 2005 - 5:00 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

The simplest way is to hack a pair of FRS radios.
They sell for as little as $17.50.
Use a transistor to switch the push-to-talk button, and a sound card to send
and receive the audio. Encode the data using a telephone modem.
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Anonymous
 
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Posted on Sunday, September 4, 2005 - 10:00 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I'm trying to build a robot and I'm wondering if I could use the computer controlled transmitter to transmit morse code to an on-board receiver (which would have a pic microcontroller to decipher the morse code). I'm thinking that maybe i could tell the robot what to do using simple commands. Thanks.
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Simon Quellen Field (Sfield)
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Post Number: 659
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Posted on Monday, September 5, 2005 - 12:15 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Sure, go for it.
You can use any code that is convenient for you.
You can make up your own code if you want better error detection and
correction, or faster response.
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physics boy (Physicsinaction)
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Posted on Tuesday, October 3, 2006 - 4:07 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Can our 1Mhz oscillator be used as a receiver to receive like radio . I mean can it be use to make a radio.
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Simon Quellen Field (Sfield)
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Posted on Tuesday, October 3, 2006 - 11:19 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

No.
But we have a coupld radio receiver projects if you want to do that.
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physics boy (Physicsinaction)
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Posted on Tuesday, October 3, 2006 - 9:59 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I see your radio projects they are great but the downfall comes for me is that they need a ground I want to build a receiver that runs only on it`s own battery power and can just turn on LED when picks up simplest signal (Range could be about 1 to 2 meters ) a buzz or anything like that from the crystal oscillator the oscillator I am using is 30MHz.
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Alex Roberts (Whoo_mythbusters)
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Post Number: 169
Registered: 9-2005
Posted on Tuesday, October 3, 2006 - 10:17 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

A ground can just be a piece of metal. Get some tin/aluminum foil, about a foot or so should work, then connect your ground on our radio to that. The radios will work without the ground, but performance is greatly compromised.
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Simon Quellen Field (Sfield)
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Post Number: 1516
Registered: 12-2004
Posted on Wednesday, October 4, 2006 - 10:59 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

The Three Penny Radio needs no extra ground or antenna.
But it won't work at 30 Mhz.
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physics boy (Physicsinaction)
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Post Number: 23
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Posted on Wednesday, October 4, 2006 - 10:02 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Through some enhancement on the project can it be made to receive that frequency.
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Simon Quellen Field (Sfield)
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Post Number: 1518
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Posted on Thursday, October 5, 2006 - 10:48 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

No.
The chip works at frequencies up to about 2 Mhz.
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physics boy (Physicsinaction)
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Post Number: 24
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Posted on Friday, October 6, 2006 - 5:45 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I was trying to build your project of computer controlled FM Transmitter . The thing I observed which I don`t understand is that I connect pin 5 and pin 4 of serial port to a LED and write a program which turn on and off DTR after 300ms interval I receive the buzz on radio at frequency about 103 Mhz why it happened can you explain and also the range was very nice more tan I got on 1Mhz oscillator.
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Simon Quellen Field (Sfield)
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Username: Sfield

Post Number: 1526
Registered: 12-2004
Posted on Friday, October 6, 2006 - 11:17 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

First off, there is no FM transmitter project on my site, computer
controlled or otherwise. There might be in the future though.

The reason you are hearing noise at 103 Mhz is that you are splattering
radio waves across all frequencies. It is called noise. You should be
able to pick it up all over both the AM and FM bands, and in between, as
well as over shortwave bands and TV bands.

This is why we have to keep the power way down, so as not to interfere
with other communications. A better designed transmitter will have a
filter on the output, so instead of square waves, we have a pure sine wave
that uses much less bandwidth, and does not stray outside of its designed
frequency.
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scott (Ichyc)
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Username: Ichyc

Post Number: 128
Registered: 6-2006
Posted on Friday, October 6, 2006 - 6:48 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

why don't you just make a sine wave generator
then it wont go out of it's frequency.
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Manuel Perez (Prz22)
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Username: Prz22

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Posted on Tuesday, March 31, 2009 - 12:03 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Hi, excuse my ignorance, but...

How can i recieve(syntonize) a 1Mhz frecuency from a Short Wave Radio or a cheap AM Radio ?

Thanks
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Theresa Simmons (Theresa)
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Username: Theresa

Post Number: 113
Registered: 1-2008
Posted on Tuesday, March 31, 2009 - 12:47 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

See "http://sci-toys.com/scitoys/scitoys/radio/am_transmitter.html".

1 megahertz is right in the middle of the frequency range that an AM radio
is designed to receive. Any amplitude modulated signal at that frequency
will make sound in an AM radio.
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Patrick (Firewire)
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Username: Firewire

Post Number: 122
Registered: 12-2007
Posted on Tuesday, March 31, 2009 - 1:05 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

If you can't get a hold of a receiver that can receive 1 Mhz, then just use an oscillator with a higher frequency that your radio can receive. But I'm better off using FM transmitters. This is a good site to start with.

It contains pictures and diagrams of simple FM circuits (1, 2 ,3 ,4 transistor FM transmitters) which you could receive using a pocket FM radio receiver, or that of your mobile phone (some mobile phones have FM radios in them).

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