audioguru

I think the low power station has at least a few thousand watts. It is a real radio station that covers the largest city in my country.

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Uncle $crooge

panic mode

i guess i meesed this one up, your circuit is fine,
i was kidding about 2 WATT output from the circuit above :-)

Hero999

audioguru,
Your circuit is also better because it has an amplifier on the output to isolate the oscillator from changes on the load like someone walking in front of it and reflecting some of the radiation back to it.

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audioguru

In my electronics career, I hardly worked with RF things.
Recently, somebody on a forum posted a simple FM transmitter circuit that didn't work so I fixed and improved it in stages. My FM transmitter is just a bunch of circuits of other people that I put together.

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Uncle $crooge

dfhrace

yes i have a question about the circuit "fmtransmitter3.gif", i wanted to know could i put a headphone jack input in place of the mic? because i was going to use this for my ipod inplace of buying an itrip so any help would be good thanks

dan

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Hmmm.....let me think......Meow!

audioguru

The headphones output level of an ipod is about 200 times higher than the level from a microphone. The entire preamp transistor stage of the transmitter must be removed.

The simple transmitter circuit is a lousy child's toy that would sound horrible:
1) Its RF frequency drifts all over the place if something gets near it or its antenna, and if its battery voltage drops.
2) It is mono, not stereo.
3) It doesn't have pre-emphasis (treble boost) like FM radio stations have, so it would sound muffled like an AM radio.

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Uncle $crooge

ilektronikos

can anyone please suggest a simple circuit for RF POWER METER for testing the oscillator output. i foun one in the site
http://electronics-diy.com/tx500.php.
i bulid the schematic below but it doesnt work.
for the 2pF i use 1pF conected parallel. in the image of the project in the
site he uses 1.8 conected in series and he 270 resistor for the emmiter insted of 1k that he has the shematic. any suggestions;
The scematic below is from the site http://electronics-diy.com/tx200.php
thanks in advance

Attached Images

power_meter.jpg (11.9 KB, 147 views)

audioguru

The power meter's circuit has the LED backwards.
Also the transistor is not biased correctly but it might work.

I don't know which 1.8, 270, 1k and emitter you are talking about.

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Uncle $crooge

Cool_buddy_57

Platonas

You are talking about the 2watt one? Anyway it is not even 1 watt.

The coil could have 5 to 6 turns on a 6 mm diameter with a 0.6 to 1 mm wire.
C1 is better to be a variable one with values up to 60 pf and C2 can be a 12 or 15 pf capacitor. The coil does not need to be a variable one but an aircore.

Regards
P.

qqqq_@

gooood
thank

blaze3927

sorry if i'm asking a stupid question. but...
would this work if i connected a headphone jack to the transmitter and put that in my ipod instead of the microphone?

Hero999

Yes but you need an attenuator (this is no problem a couple of resistors will do) and simple transmitter circuits like this give crap mono AM radio sound quality.

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manish jain

hi
thanks for reply
but i have no idea plz can u send project diagram & some detail on my e mail id
manishjainshah@yahoo.co.in

manish jain

can u send some theory related to it