Mini FM Transmitter

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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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.

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kensmith@rahul.net   forging knowledge
Reply to
Ken Smith

transmitter.

hands on?

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.

Reply to
fred_stevens

in article snipped-for-privacy@news.xsall.nl, Wouter van Ooijen

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at snipped-for-privacy@voti.nl wrote on 2/10/05 5:44 AM:

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

Reply to
Jon Yaeger

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

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Reply to
Wouter van Ooijen (www.voti.nl

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.

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Many thanks,

Don Lancaster
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Reply to
Don Lancaster

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.

Reply to
larwe

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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Reply to
Ian Stirling

'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)

Reply to
Ian Stirling

Go here

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and search for kit KC5341. This is a PLL TX with a choice (by dip-switch) of 8 frequencies in the FM band.

Reply to
Bill Bailley

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

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Reply to
Joerg

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