Trouble building the am radio transmi... Science Toys | Science Blog | Log Out | Topics | Search
My Toys | Energy | Moderators | Register | Edit Profile

Scitoys Message Board » I am having trouble building one of the toys » Trouble building the am radio transmitter « Previous Next »

Author Message
Top of pagePrevious messageNext messageBottom of page Link to this message

Andrewww
Posted on Saturday, October 25, 2003 - 3:14 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I have a problem.I didn't found an oscillator with 4 pins,but I have a 4mhz oscillator with only 2 pins and I don't know how to connect it.Here's what it's
written on it FT 4.000 MHz.Is this suitable?If yes,please tell me how to connect it
Top of pagePrevious messageNext messageBottom of page Link to this message

Simon Quellen Field (Sfield)
Posted on Saturday, October 25, 2003 - 3:18 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

What you have is a crystal.
It is used in an oscillator to control the frequency.
An oscillator has the electronics needed to excite the
crystal and produce a waveform.

Also, a 4 megahertz oscillator will not produce signals
you can pick up with an AM radio, since the radio can
only tune between 0.500 megahertz and 1.8 megahertz.

You can buy a 1 megahertz oscillator here.
Top of pagePrevious messageNext messageBottom of page Link to this message

Andrewww
Posted on Saturday, October 25, 2003 - 3:38 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Thanks.One more question:what should I add to the Three peny radio to make the signal strong enought so I can hear it with an 8 ohm 2W speaker(without using the Piezoelectric phones)?
Top of pagePrevious messageNext messageBottom of page Link to this message

Simon Quellen Field (Sfield)
Posted on Saturday, October 25, 2003 - 5:23 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

What you need is an amplifier.
Because amplifiers are not in as much demand as radios,
an amplifier will generally cost more than a radio that
has one built-in.

You can build your own amplifier.
Do a Google search on "audio amplifier" for more information.
Top of pagePrevious messageNext messageBottom of page Link to this message

Andrewww
Posted on Thursday, October 30, 2003 - 1:40 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I have another problem.Tha guy from the electronics store sais there is no such thing as an audio transformer.He sais transformers are only measured in V not in ohms.What should I do?
Top of pagePrevious messageNext messageBottom of page Link to this message

Simon Quellen Field (Sfield)
Posted on Friday, October 31, 2003 - 1:14 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Find a different person to talk to.
Someone who actually knows something.

Try doing a Google search for "audio transformer".
Then print out the results page and bring it in to the
store with you, to show the idiot he is wrong.

Or you could just buy the transformer from our
catalog.
Top of pagePrevious messageNext messageBottom of page Link to this message

Anonymous
Posted on Monday, April 19, 2004 - 8:17 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

does the FM band beging at 20 MHz?
Top of pagePrevious messageNext messageBottom of page Link to this message

Simon Quellen Field (Sfield)
Posted on Monday, April 19, 2004 - 8:32 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

No.
Just look at your FM radio.
It starts at 88 Mhz, and goes up to 108 Mhz.
Top of pagePrevious messageNext messageBottom of page Link to this message

Alexander N Roberts (Whoo_mythbusters)
Member
Username: Whoo_mythbusters

Post Number: 12
Registered: 9-2005
Posted on Sunday, November 20, 2005 - 10:38 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

I have an old Radio Shack electronics lab that has a prodject on building an AM transmiter. They dont seem to use a crystal occilator i was wondering what they use to subsitute for this. This kit is called 300 in One Electronic Project Lab Cat. No. 28-270 thanks
Top of pagePrevious messageNext messageBottom of page Link to this message

Simon Quellen Field (Sfield)
Senior Member
Username: Sfield

Post Number: 786
Registered: 12-2004
Posted on Monday, November 21, 2005 - 12:22 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

They probably use a resistor and capacitor, or a coil and capacitor,
as the tuning element, and a transistor or two as the amplifying
element. It will be sensitive to changes in temperature and voltage,
and will thus not keep a constant frequency. It will also have many
more connections than the simple transmitter I described, since mine has
all the transistors and the tuning element all combined in one part.
Top of pagePrevious messageNext messageBottom of page Link to this message

Jon Vote (Jon779)
New member
Username: Jon779

Post Number: 1
Registered: 12-2007
Posted on Friday, December 21, 2007 - 12:42 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Hi - I'm having trouble with the AM Transmitter Kit. The ocilator clearly works fine, but I'm not able to modulate any audio to the signal. I tried using the earphone jack from a radio, a crystal mike, a non-crystal mike, with the transformer, without and the tranformer, reversed the impedance - etc. Nothing works. Any suggestions?

Thanks!
Top of pagePrevious messageNext messageBottom of page Link to this message

Simon Quellen Field (Sfield)
Senior Member
Username: Sfield

Post Number: 1815
Registered: 12-2004
Posted on Friday, December 21, 2007 - 10:14 am:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

It sounds like your signal source does not have a low enough
impedance to drive the transformer. Find a radio that uses an
8 ohm earphone, and turn the volume up.
Top of pagePrevious messageNext messageBottom of page Link to this message

Jon Vote (Jon779)
New member
Username: Jon779

Post Number: 2
Registered: 12-2007
Posted on Friday, December 21, 2007 - 6:50 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Yes! Using another source did the trick.

One more question - I was hoping to set this up so my granddaughter could play DJ. Do you know how I could use this with a microphone? Do I need a pre-amp or something.

Thanks!
Top of pagePrevious messageNext messageBottom of page Link to this message

Simon Quellen Field (Sfield)
Senior Member
Username: Sfield

Post Number: 1816
Registered: 12-2004
Posted on Friday, December 21, 2007 - 7:19 pm:   Edit PostDelete PostView Post/Check IPPrint Post   Move Post (Moderator/Admin Only)Ban Poster IP (Moderator/Admin only)

Yes, you will need an amplifier.

Add Your Message Here
Post:
Username: Posting Information:
This is a private posting area. Only registered users and moderators may post messages here.
Password:
Options: Enable HTML code in message
Automatically activate URLs in message
Action:
For those who have trouble spelling, the Google Toolbar (included in the Google Pack) can check and correct the spelling in your posts on this message board and others.

Renewable Energy

Topics | Last Day | Last Week | Tree View | Search | Help/Instructions | Program Credits Administration