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


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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thegeeke5 years ago
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. :(
Hmm. No antenna ? What frequency is this thing supposed to use ?
damianzuch (author)  steveastrouk5 years ago
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
You need an antenna. Its being seriously restricted by the absence of one.

Steve
damianzuch (author)  steveastrouk5 years ago
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
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
.  +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).