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RF Generators Answered

Just wanted to know if Function Generators were the same as RF Generators? I'm looking for a cheap RF for a project and when I put in "RF Generator" in eBay, it comes up with Function, Signal, and Linear Generators as well. Thanks.


I have a cat with feline dementia.I was reading an article describing how researchers have discovered that cellphone radiation improves the condition of mice bred to develop Alzheimer s.
What would it take to build an RF generator operating at cellphone frequencies? Just curious..

. A Function Generator just outputs a sine/square/triangle/etc wave, usually with a user settable frequency. . RF just refers to the frequencies commonly encountered with radios. . If the function generator will operate in the RF range, then your all set. If you are wanting to transmit, you will need a power amplifier.

Thanks. I'm gonna need a RF amp for my project anyways and as long as it works out, I'll try to post an instructable on it :)

For such low frequencies (up to 1000 khz = 1 mhz),
you can possibly do well with an audio amplifier circuit.
For example the LM386 chip probably can amplify 100 khz to
around 100 milliwatts. Maybe 5 watts out of an LM383.

Which reminds me, I saw a circuit for transmitting 1000 khz
made out of an LM317 voltage regulator about a month ago...
That's a 1-amp chip! Oh, Here it is!
Voltage regulator used as transmitter

If you didn't mind: (1) building it (an 8 pin IC, two resistors, and 2 capacitors), and (2) that the output is a square wave (meaning it has the fundamental, plus the third harmonic (three times as high) the fifth, the seventh, the ninth, etc., in ever decreasing amounts - that is what a square wave is; see the picture at http://mathworld.wolfram.com/FourierSeriesSquareWave.html for how each harmonic contributes to the shape of the square wave), then the LM555 IC, running in astable mode, could do the task. http://www.national.com/ds/LM/LM555.pdf .
You can power it with from 5 to 15 volts; its output swings almost down to ground and almost up to the power supply voltage and can supply up to 200 mA. By choosing the two resistors and the 1 capacitor sizes, you can vary its period of oscillation from hours to microseconds (yes, it can oscillate at 1 MHz). The LM555 costs $1.49 at Radio Shack; the resistors and capacitor $1.00 each (being overpriced). For what it does, it's a sweet chip. Great for toys, from timing applications to a metronome to an electronic organ; from a car burglar alarm to a touch switch to pulse width modulation applications.

Another way is to buy a clock oscillator, a little 14 pin metal package; you purchase it for the frequency you want. Again, the output is a square wave. They are mostly crystal controlled, and run from 1 MHz to 20 MHz; you could divide the output down by half (multiple times) with another IC such as the CD4017 to get to the frequency you want.

If the purity of your sine waveform is important, then a tank circuit based oscillator would be best.


10 years ago

What frequency RF do you need?

I need from around 5-30 KHz up to 100-400 KHz (basically AM range)... but if I'm gonna be dishing out a lot of money for one, I'd like to try and get one with a larger range (never know if/when you might need them).

If I'm unable to get one, I'll just make a variable tank circuit, though it won't be as good as a professionally made one :P

The average function generator's top end is 1 to 10 MHz. If you want output at or below 1 MHz, a lowly LM555 IC could generate a square wave, dirt cheap; it could easily drive some output transistors providing you a fair amount of power.