I've seen tons of posts about converting FM signals to AM signals
(say, to use with an AM only vintage car radio). But I haven't seen
anything about the inverse: converting an AM signal to an FM signal
(because there are quite a few FM-only devices on the market now, such
as MP3 players). I found this: http://www.uashem.com/pageid-259.html ,
but it doesn't really fit my criteria. I'd like to be able to tune in
any AM station, and then select the frequency to output it to without
interfering with other station (think iPod transmitter).

Surely there's gotta be some out there...

In message . com,
ungvichian writes
I've seen tons of posts about converting FM signals to AM signals
(say, to use with an AM only vintage car radio). But I haven't seen
anything about the inverse: converting an AM signal to an FM signal
(because there are quite a few FM-only devices on the market now, such
as MP3 players). I found this: http://www.uashem.com/pageid-259.html ,
but it doesn't really fit my criteria. I'd like to be able to tune in
any AM station, and then select the frequency to output it to without
interfering with other station (think iPod transmitter).

Surely there's gotta be some out there...


Presumably you are thinking about a transmitter like this?
http://www.techfocus.co.uk/iTrip-FM-...ters/TFM07.htm
I bought one last week, and it seems to work OK.

I don't think that you can really convert AM to FM in a controlled way,
without going to baseband audio first. I reckon that the regen circuit
you found relies more on 'act of God' or 'green fingers (thumbs)' than
science.

Ian.
--

On Mar 25, 11:11?pm, "ungvichian" wrote:
I've seen tons of posts about converting FM signals to AM signals
(say, to use with an AM only vintage car radio). But I haven't seen
anything about the inverse: converting an AM signal to an FM signal
(because there are quite a few FM-only devices on the market now, such
as MP3 players). I found this:http://www.uashem.com/pageid-259.html,
but it doesn't really fit my criteria. I'd like to be able to tune in
any AM station, and then select the frequency to output it to without
interfering with other station (think iPod transmitter).

Surely there's gotta be some out there...

If you need a small "converter" (of audio), all you need is a
frequency-modulated oscillator, the oscillator tuned to the
FM BC band of your choice. It can be a single transistor
with something like a simple variable capacitance diode (or
equivalent) doing the FM.

The circuit shown in your reference has no magic conversion
and is little more than a jammer of everyone in its tuning
range. If it works at all then it would be by overloading the
input of an FM BC band receiver and forcing it to be a mixer.
That is NOT good homebrewing since the same single-
transistor circuit could be converted to an FMed oscillator
with its output attenuated (to avoid undue radiation) and
loosely coupled to the FM receiver. If you have audio, even
if only from the speaker of an AM receiver, then you have
the modulation source...at audio, something you can hear
to make sure there IS a modulation signal input.

73, Len AF6AY

I'd suggest an MK484-style MW receiver that feeds a simple common base
VCO like your average "FM Bug" circuit. Needs only a slack handful of
components, fits in a matchbox and would run from a pair of AA cells for
days.

ungvichian wrote:
I've seen tons of posts about converting FM signals to AM signals
(say, to use with an AM only vintage car radio). But I haven't seen
anything about the inverse: converting an AM signal to an FM signal
(because there are quite a few FM-only devices on the market now, such
as MP3 players). I found this: http://www.uashem.com/pageid-259.html ,
but it doesn't really fit my criteria. I'd like to be able to tune in
any AM station, and then select the frequency to output it to without
interfering with other station (think iPod transmitter).

Surely there's gotta be some out there...


--
Alan Yates
http://www.vk2zay.net/
The Moon is Waning Crescent (12% of Full)