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Seeking advice on boosting range of fm transmitter (from a kid's toy) Answered


Hi all,

I just bought the Smartlab: You Build It - Rock Star Microphone toy from a Goodwill. It's a great toy; it has a microphone that let's me transmit my voice over the radio (perfect for a Halloween haunted house when the static-mad radio bursts to life with terrifying voice-overs!!!:) works but only up to about a six foot range. 

I would like to be in a different room and use the microphone but I need to boost the range considerably - I understand that the FCC has rules about this. Moving forward, I don't know how to do this (at all....). Are there commercial range boosters that I can use? Are there mods that someone can recommend? Are these toys designed to NOT transmit beyond six feet even with mods? I wish I could give more information about the tech specs of the toy but I will have to try to de-solder the metal plate covering the circuit board (plus I don't know what specs to look for yet).

Advice appreciated,

DAZU


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thegeeke (author)2011-09-20

Be very careful... those FCC rules that you might take lightly can really burn you if you aren't careful... I had a run-up with them... it wasn't pleasant. Evidently it's much easier to enforce those rules than most people think. :(

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steveastrouk (author)2011-09-10

Hmm. No antenna ? What frequency is this thing supposed to use ?

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damianzuch (author)steveastrouk2011-09-10

Here's what the manual says:


it has four settings:
position 1 is

Analog: 97.0 - 98.0 FM
Digital: 97.0 - 98.0 FM

position 2 is 97.8 - 99.0 FM
position 3 is 98.6 - 99.8 FM
position 4 is 99.4-100.6 FM

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steveastrouk (author)damianzuch2011-09-10

You need an antenna. Its being seriously restricted by the absence of one.

Steve

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damianzuch (author)steveastrouk2011-09-11

Could you tell me more? Is there a specific type of antenna that optimizes the range? Alternatively, could I strip an antenna off an old r/c toy controller and use that? Also, are there specifications as to where on the circuit I would put the antenna?

Sorry for the load of questions but I figure it's better to ask than to fry the circuit unintentionally!

Thanks,

DAZU

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steveastrouk (author)damianzuch2011-09-11

Well this thing is designed to work right in the broadcast bands for FM radio, so be careful. Are there any wires coming out that "don't do anything" ?

STeve

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NachoMahma (author)steveastrouk2011-09-11

.  +1
.  If an antenna doesn't give you the range you need, you will probably need a linear amplifier. IIRC, ~100mW will give you ~1/4 mile range (using the FM radio band under optimum conditions).

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