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boohickey11
Posted on Saturday, January 17, 2004 - 10:13 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I built the Three penny radio and it worked perfectly. I also built the Transmitter. It doesn't work. I've checked and double and triple checked and the whole thing is built exactly right. When the battery is in it works like a jammer. Any nearby radios tuned at 1000 KHz will stop getting any of the reception from our 970 KHz Station. I think that maybe the Transformer isn't doing its job. The number on the top of the transformer is 60-282-0 if that helps.
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Simon Quellen Field (Sfield)
Posted on Saturday, January 17, 2004 - 10:48 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

There is a discussion about this in another place in this message board.
Some of what is discussed there does not apply to you, since your
oscillator is obviously working fine. But this part may help:

If the oscillator is working (as evidenced by the quieting of the static) then you need to check the modulation. Is your audio source designed to operate an 8 ohm earphone? If it is designed for 16 or 32 ohm headphones, it will probably not work very well. You can try raising the volume control on the radio you use as the signal source.
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boohickey11
Posted on Saturday, January 24, 2004 - 10:40 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I have a multimeter. How can I check the ohms of my earphone source?
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Simon Quellen Field (Sfield)
Posted on Saturday, January 24, 2004 - 10:44 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Unfortunately, checking impedance is not as easy as
checking resistance. A multimeter won't do it. The
easiest way is to contact the manufacturer.
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Anonymous
Posted on Friday, January 30, 2004 - 11:00 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

We are building the laser transmitter. On the transmitter side, the beam does not appear to be variable with the transmitting radio on(radio#1). On the receiving side, we are using the cadium pizoelectric photocell connected to a 1.5 volt battery then to the earphone jack of radio#2. The other side of the photocell is connected to the other terminal of the earphone jack on radio#2. With the laser on, the volume of radio#2 high, and the transmitting radio off we get no signal or humm. With radio #1 on we still do not get any audio or humm. Can you please give us any help? This would be greatly appreciated. Thanks:)
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Simon Quellen Field (Sfield)
Posted on Friday, January 30, 2004 - 11:06 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

You are trying to receive the signal by putting it into the output
of a second radio? You need either an amplifier, or a sensitive
earphone.
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Anonymous
Posted on Saturday, January 31, 2004 - 6:51 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

For the laser transmitter, do you need the resistor on both the transmitter and the reciever? Is it used with the pizoelectric photcell or just the solar panel? What kind of amplifier do I need on the recieving end? I have been using a speaker-amplifier, but blew it out. This project looks fantastic. Thanks very much.
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Simon Quellen Field (Sfield)
Posted on Saturday, January 31, 2004 - 7:01 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

A resistor is not needed.

Some people are zapping their lasers, probably with
static electricity from their fingers, but also possibly with
a surge from the transformer when powered by large batteries.
These people might benefit from an extra resistor in series with
the laser. Note that the laser already has a series resistor
on the circuit board, designed to limit the current from the
small batteries that come with the laser.

It seems unlikely to me that a solar cell could have blown out
your amplifier. Perhaps it was ready to go anyway, or you
were sending a large current through it using a battery.
The solar cell and piezoelectric earphone make an excellent
receiver, and not expensive amplifier or batteries are needed.
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Anonymous
Posted on Tuesday, February 10, 2004 - 7:46 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I am using a speaker amplifier for the laser transmitter. Will this work? Also, I took a earphones with a radio jack on the end. I then spliced the wires in it and connected each one to the 2 pronged side of the transformer with the jack going into the radio. Is this ok? Thank you for your time.
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Simon Quellen Field (Sfield)
Posted on Tuesday, February 10, 2004 - 8:24 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

That all sounds fine.
What troubles are you having?

Have you read the notes in the messages above?
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Kate
Posted on Wednesday, February 11, 2004 - 4:32 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I am doing the laser transmitter as part of my science project and am wondering if there are any other webpages that describe how to build a laser transmitter. I need more than one source for my project. Thanks
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Simon Quellen Field (Sfield)
Posted on Wednesday, February 11, 2004 - 7:36 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Well, I like to be unique... ;-)

There should be lots of information on "laser communications" as a Google
search term. Lots of Amateur Radio enthusiasts also play with laser
communications. None are as simple as what I have on my site, but they
should be perfect for a bibliography.
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christopher
Posted on Sunday, February 15, 2004 - 12:05 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

i built the laser comunicator for science fair and i'm going to the regional science fair competition but the laser pointer dot is dim when attached to the system but if i just use it alone it works just fine. am i doing anything wrong?
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Simon Quellen Field (Sfield)
Posted on Sunday, February 15, 2004 - 4:25 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

If you are receiving the voice signal with the dim laser,
then everything is going fine. The laser is dim because
less current is being used, and this will keep the laser
working for a longer time than a higher current will.

You can raise the voltage in order to raise the current
in the laser. However, you risk damaging the laser. Make
sure you have some spare lasers around while you experiment.
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Anonymous
Posted on Saturday, February 21, 2004 - 12:36 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

ok thanks
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alvin fraser (Asafraser)
New member
Username: Asafraser

Post Number: 1
Registered: 8-2005
Posted on Wednesday, August 10, 2005 - 4:48 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

i try to build a bugg but i cant get the 2 main capastor i need 6.8pf and 1.8 is there anything i can do.
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Simon Quellen Field (Sfield)
Senior Member
Username: Sfield

Post Number: 613
Registered: 12-2004
Posted on Wednesday, August 10, 2005 - 5:17 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Google for Digikey, Jameco, or "electronics parts".
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drew psycoboy wilson (Unregistered Guest)
Unregistered guest
Posted From: 152.163.101.8
Posted on Monday, February 13, 2006 - 7:01 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

what ive got so far im having troble finding the photo electric sensor you have specifed could you give me some tips on where to find one
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Simon Quellen Field (Sfield)
Senior Member
Username: Sfield

Post Number: 1057
Registered: 12-2004
Posted on Wednesday, February 15, 2006 - 11:41 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

We sell solar cells in our catalog.
If you want the cadmium sulfide photoresistor (cheaper but not as good
as a solar cell), you can find those all over the place.
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Nafee Sarwar (Nafee)
New member
Username: Nafee

Post Number: 2
Registered: 10-2008
Posted on Thursday, October 30, 2008 - 1:40 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I am building the AM transmitter. Can you please give the measurements of the tranformer in voltage because I live in Bangladesh and it is very hard to get stuff here related to electronics, they are available but the shopkeepers have there own language and they may call certain things by the name which the electronic community uses. They are also mostly uneducated so 8 to 1k ohm transformer they will not understand.

Another HUGE problem I have is that I cannot buy from internet because my mother will not let me use the credit card, but the 1 MHz crystal is not available here in stores, they only sell 2, 4, 12, 14, 7, 40 MHz and many others but not below 2. So can you tell me how to build your transmitter design using a 2 MHz crystal instead a 1 MHz one or tell me some devices like computers where I can take a !MHz oscillator but it is better if you tell me the alternative to 1 MHz crystal and if I can use any other frequency. There are other channels besie AM and FM and one as a 2MHz in there range so just tell me how to build a transmitter using 2 and 4 or 3 MHz crystal.And this is reall really urgent my science fair is on November 4th. ANd I am using a solderless breadboard instead of a generic circuit board(cause its hard to find here)

(Message edited by nafee on October 30, 2008)
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Simon Quellen Field (Sfield)
Senior Member
Username: Sfield

Post Number: 1919
Registered: 12-2004
Posted on Thursday, October 30, 2008 - 5:21 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Audio transformers are not rated by voltage. That is for power transformers,
which will not work. Audio transformers are rated by the impedances (input
and output) such as 1200 ohms to 8 ohms. You can get one out of an old radio
receiver.

The AM broadcast band is limited to the range of 0.54 megahertz to 1.6
megahertz. Only frequencies in this range can be received by an AM radio.
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Simon Quellen Field (Sfield)
Senior Member
Username: Sfield

Post Number: 1920
Registered: 12-2004
Posted on Thursday, October 30, 2008 - 5:21 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Audio transformers are not rated by voltage. That is for power transformers,
which will not work. Audio transformers are rated by the impedances (input
and output) such as 1200 ohms to 8 ohms. You can get one out of an old radio
receiver.

The AM broadcast band is limited to the range of 0.54 megahertz to 1.6
megahertz. Only frequencies in this range can be received by an AM radio.
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Nafee Sarwar (Nafee)
New member
Username: Nafee

Post Number: 3
Registered: 10-2008
Posted on Friday, October 31, 2008 - 5:46 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I know what the AM band is but can't I use another oscillator or another channel? there are other channels other than AM and FM..and on a radio reciever of mine i saw that the frequency meter has 4 different channels and one of it has 2 to 8 MHz on it. So can you tell me an alternative to an AM or FM transmitter..?

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