# In need of help - RF circuit for frequencies between 10Hz & 25kHz

Discussion in 'The Projects Forum' started by whoelse2u, Feb 8, 2016.

1. ### whoelse2u Thread Starter New Member

Feb 8, 2016
3
0
For a hobby project I have, I need to make a circuit that will transmit a radio frequency between 10Hz and 25kHz. I don't need to know the specific frequency being emanated so I'm fine with controlling the frequency with a variable potentiometer. I'm aware of the issue of RF interference in this spectrum so I only need something with enough power to send the signal about ten feet. I would expect to run this thing off AA batteries.
It would be an added plus if a speaker jack could be included in the circuit so that, for frequencies in the human hearing range, I would be able to plug in my headphones to hear the same frequency as the RF signal.
I have a very basic working knowledge of electronics.
What do you think? Is there an easy way to do this?

2. ### #12 Expert

Nov 30, 2010
16,685
7,327
10 Hz to 25KHz is not in the RF range. You can't transmit audio unless your antenna is several miles long.

3. ### Papabravo Expert

Feb 24, 2006
10,340
1,850
Well you can try, but your success will be limited.

4. ### crutschow Expert

Mar 14, 2008
13,497
3,373
You could perhaps transmit and receive over a narrow audio frequency range by used a tuned ferrite coil for the transmitter and receiver but that wouldn't work for the wide frequency range you want.

5. ### Picbuster Member

Dec 2, 2013
391
53
make a Wien bridge oscillator as descripted in an other, recent post.

6. ### whoelse2u Thread Starter New Member

Feb 8, 2016
3
0
AAC Fanatic! Thanks for the feedback. I'm a little embarrassed at the stupidity of my question. What if I redefine the project as follows:

For a hobby project I have, I need to make a circuit that will send an electrical signal (perhaps a sine wave generator??) through an induction coil at frequencies between 10Hz and 25kHz. I don't need to know the specific frequency being emanated so I'm fine with controlling the frequency with a variable potentiometer. I would expect to run this thing off AA batteries.

It would be an added plus if a speaker jack could be included in the circuit so that, for frequencies in the human hearing range, I would be able to plug in my headphones to hear the same frequency as what is going through the coil.

Maybe one way to combine the two would be to have a circuit that sends the sine wave to a "moving coil loudspeaker". Can I use a digital oscillator circuit like this one http://www.electroschematics.com/2957/digital-sinewave-oscillator/?

Maybe this high frequency wave form generator is the proper circuit that will do it all http://www.electroschematics.com/2741/high-frequency-generator/.

What do you think? What would you suggest for the +- 5 volt power source?