Mini FM Transmitter
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Mini FM Transmitter

 
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Guest
Posted: Thu Feb 10, 2005 7:03 am    Post subject: Mini FM Transmitter Reply with quote
I have looked around but have not yet found a GOOD mini FM transmitter.
Smaller the better. Anyone know of plans or schematic I can get my hands on?

Thanks!!

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Ken Smith
Guest
Posted: Thu Feb 10, 2005 7:03 am    Post subject: Re: Mini FM Transmitter Reply with quote
In article <bqyOd.5714$ds.2474@okepread07>, . <abel6479@cox.net> wrote:
Quote:
I have looked around but have not yet found a GOOD mini FM transmitter.
Smaller the better. Anyone know of plans or schematic I can get my hands on?

Thanks!!

I remember Pop-tronics had one using a tunnel diode that was very small.
You could hide it under a penny.


How much range do you need? That sort of sets the limit on size.

At very short ranges, a one transistor design can work ok.


--
--
kensmith@rahul.net forging knowledge
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Wouter van Ooijen (www.vo
Guest
Posted: Thu Feb 10, 2005 4:44 pm    Post subject: Re: Mini FM Transmitter Reply with quote
Quote:
I have looked around but have not yet found a GOOD mini FM transmitter.
Smaller the better. Anyone know of plans or schematic I can get my hands on?

define GOOD. low frequency drift (no 'hand effect') rules out most
1-transistor designs. What do you consider small?

Kitsrus has some FM transmitter kits. (I sell most of them).




Wouter van Ooijen

-- ------------------------------------
http://www.voti.nl
Webshop for PICs and other electronics
http://www.voti.nl/hvu
Teacher electronics and informatics

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Jon Yaeger
Guest
Posted: Thu Feb 10, 2005 7:44 pm    Post subject: Re: Mini FM Transmitter Reply with quote
in article 420b3ab6.1208488604@news.xs4all.nl, Wouter van Ooijen www.voti.nl
at wouter@voti.nl wrote on 2/10/05 5:44 AM:

Quote:
I have looked around but have not yet found a GOOD mini FM transmitter.
Smaller the better. Anyone know of plans or schematic I can get my hands on?

define GOOD. low frequency drift (no 'hand effect') rules out most
1-transistor designs. What do you consider small?

Kitsrus has some FM transmitter kits. (I sell most of them).




Wouter van Ooijen

-- ------------------------------------
http://www.voti.nl
Webshop for PICs and other electronics
http://www.voti.nl/hvu
Teacher electronics and informatics


I designed an SMT stereo transmitter around the Rohm BH1417F IC. I might
also be able to come up with a PCB. The BH1417 series has a PLL that
reduces frequency drift; the BA series drifts with temperature.

E-mail me for a copy of the schematic & etc.
Jon
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Guest
Posted: Thu Feb 10, 2005 10:00 pm    Post subject: Re: Mini FM Transmitter Reply with quote
.. wrote:
Quote:
I have looked around but have not yet found a GOOD mini FM
transmitter.
Smaller the better. Anyone know of plans or schematic I can get my
hands on?

Thanks!!

Maxim have a stereo VCO chip that can be used as a stereo FM
transmitter. They have an application note with the circuit. It's a
very small chip though!

Fred.
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Ian Stirling
Guest
Posted: Fri Feb 11, 2005 4:15 am    Post subject: Re: Mini FM Transmitter Reply with quote
Ken Smith <kensmith@green.rahul.net> wrote:
Quote:
In article <bqyOd.5714$ds.2474@okepread07>, . <abel6479@cox.net> wrote:
I have looked around but have not yet found a GOOD mini FM transmitter.
Smaller the better. Anyone know of plans or schematic I can get my hands on?

Thanks!!

I remember Pop-tronics had one using a tunnel diode that was very small.
You could hide it under a penny.

How much range do you need? That sort of sets the limit on size.

Power supply generally more important.
Modern transistors are so small that the battery will be bigger.
Hell, the smallest cell (4mmdia*2 height) is the size of several transistors
by itself.
>
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Guest
Posted: Fri Feb 11, 2005 6:11 am    Post subject: Re: Mini FM Transmitter Reply with quote
Quote:
Mini-FM transmitters that are not crystal derived stable are useless
since they cannot be received on the majority of modern FM tuners.

As long as there is a manual tuning adjustment on one or other of tx or
rx, it CAN be received (though possibly not optimally) even on modern
digital tuners. I have commercial CD/MP3-to-FM car adapters that work
this way, and nary a crystal to be found.
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Don Lancaster
Guest
Posted: Fri Feb 11, 2005 6:11 am    Post subject: Re: Mini FM Transmitter Reply with quote
Ian Stirling wrote:
Quote:
Ken Smith <kensmith@green.rahul.net> wrote:

In article <bqyOd.5714$ds.2474@okepread07>, . <abel6479@cox.net> wrote:

I have looked around but have not yet found a GOOD mini FM transmitter.
Smaller the better. Anyone know of plans or schematic I can get my hands on?

Thanks!!

I remember Pop-tronics had one using a tunnel diode that was very small.
You could hide it under a penny.


How much range do you need? That sort of sets the limit on size.


Power supply generally more important.
Modern transistors are so small that the battery will be bigger.
Hell, the smallest cell (4mmdia*2 height) is the size of several transistors
by itself.


Mini-FM transmitters that are not crystal derived stable are useless
since they cannot be received on the majority of modern FM tuners.

The Radio Shack unit is not half bad.
Schematics on my website.


--
Many thanks,

Don Lancaster
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
voice: (928)428-4073 email: don@tinaja.com

Please visit my GURU's LAIR web site at http://www.tinaja.com
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Ian Stirling
Guest
Posted: Fri Feb 11, 2005 6:07 pm    Post subject: Re: Mini FM Transmitter Reply with quote
Don Lancaster <don@tinaja.com> wrote:
Quote:
Ian Stirling wrote:
Ken Smith <kensmith@green.rahul.net> wrote:

In article <bqyOd.5714$ds.2474@okepread07>, . <abel6479@cox.net> wrote:

I have looked around but have not yet found a GOOD mini FM transmitter.
Smaller the better. Anyone know of plans or schematic I can get my hands on?

Thanks!!

I remember Pop-tronics had one using a tunnel diode that was very small.
You could hide it under a penny.


How much range do you need? That sort of sets the limit on size.


Power supply generally more important.
Modern transistors are so small that the battery will be bigger.
Hell, the smallest cell (4mmdia*2 height) is the size of several transistors
by itself.


Mini-FM transmitters that are not crystal derived stable are useless
since they cannot be received on the majority of modern FM tuners.

'cannot' is probably a bit strong.
95% of tuners I've owned will work just fine with this, as they
recieve signals when tuned 'off by one' just fine.

(50Khz spacing)
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Bill Bailley
Guest
Posted: Sat Feb 12, 2005 6:10 am    Post subject: Re: Mini FM Transmitter Reply with quote
"." <abel6479@cox.net> wrote in message
news:bqyOd.5714$ds.2474@okepread07...
Quote:
I have looked around but have not yet found a GOOD mini FM transmitter.
Smaller the better. Anyone know of plans or schematic I can get my hands
on?

Thanks!!



Go here http://www1.jaycar.com.au/ and search for kit KC5341. This is a
PLL TX with a choice (by dip-switch) of 8 frequencies in the FM band.
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Joerg
Guest
Posted: Sun Feb 13, 2005 3:40 am    Post subject: Re: Mini FM Transmitter Reply with quote
Hello,

Just came back from Walmart. They had one for about $20, four
programmable channels which may even be PLL controlled because there
was just a single button on it. Stereo, too. The whole thing was smaller
than a cigarette pack.

Why build if they are this cheap?

Regards, Joerg

http://www.analogconsultants.com
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