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Sine Wave

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EllaZ

New Member
Hello to all...
I am a student and am interested in making a sine wave producer. Specifically one that produces 8 to 10Hz.
I have absolutely no idea where to start and would love help.
Thanks in advance.
 
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alec_t

Well-Known Member
Most Helpful Member
Welcome to ETO!
What are the voltage, current and output impedance requirements of the producer? What will it be used for?
 

Mikebits

Well-Known Member
Welcome to ETO!
What are the voltage, current and output impedance requirements of the producer? What will it be used for?
Based on the way the question was worded, I doubt the OP can answer most of those questions... Maybe the what for :)
 

EllaZ

New Member
It will be used in a series of expironments to test the effects of 8 to 10 Hz on various subjects. I don't actually have any requirements alec_t.
 

ChrisP58

Well-Known Member
Most Helpful Member
Do you want to build one, or do you just need an instrument that can product the sine wave?

If you just need an instrument, search google, ebay, or other sites for "Function Generator"

You'll find lot's of ready made boxes that will give you what you need. Most should be able to cover that range, but double check the specs before you buy.

Note: A function generator will give you a small, signal level voltage, typically about 1 volt. If you need the sine wave at a higher voltage, or in a different form, you'll need may need an amplifier and/or transducer.
 

alec_t

Well-Known Member
Most Helpful Member
It will be used in a series of expironments to test the effects of 8 to 10 Hz on various subjects.
If those subjects include humans, be aware of the dangers. From what I've read, frequencies around 7Hz can trigger epileptic seizures in susceptible people.
So, what sort of power level do you have in mind? Microwatts? Kilowatts? .....
How will the signal be imposed on the subject? Electrically? Magnetically? Acoustically? ....
 

AnalogKid

Well-Known Member
Most Helpful Member
If your goal is to build a circuit from scratch, I recommend the phase shift oscillator and bubba oscillator circuits. Conceptually simple, easy design math, excellent stability, reasonable distortion, low cost. If you need precise frequency control or very tight amplitude stability, there are other circuits.

ak
 

large_ghostman

Well-Known Member
Most Helpful Member
Is this microbe or plant based testing? Specifically root growth tip tests? or microbe colonie growth?
 

Mikebits

Well-Known Member
Didn't the Mythbusters do something with 10Hz Brown note frequency. As I recall Myth Busted :woot:
 

large_ghostman

Well-Known Member
Most Helpful Member
Didn't the Mythbusters do something with 10Hz Brown note frequency. As I recall Myth Busted :woot:
They did yes, but they didnt do it right, vibrate the bowl at 10Hz ;), I cant see sound doing it but there you go. there are some biology experiments at these frequencies but one of the experiments is wrong! its a well known secret that some text books have had the experiment in for 40 years and the frequency given was a typo!! Even today you get new text books with the same mistake in lol.

Root tips can be affected at certain frequencies (the meristem part) but some assume you use a electric field (you can) but normally its done with vibration, the electric field has a slightly different affect but TBH its nothing exciting! the microbe one I have seen quoted at 10Hz for splitting open algae cells for bio fuels. This is WRONG!! its around 20,000 kHz but depends on the species and needs a decent transducer to get it to work right.

Some bacteria will grow on a plate in a straight line if you use 8Hz
 

audioguru

Well-Known Member
Most Helpful Member
The PA speakers used by the Mythbusters were for voices and could not produce low frequencies. Most real sub-woofers cannot even produce 10Hz. A mechanical contraption using an electric motor and a crankshaft would produce 10Hz pretty well and cause the brown stuff to fly all over the place!:eek:
 

tomizett

Active Member
The PA speakers used by the Mythbusters were for voices and could not produce low frequencies
They where 2x18" subwoofers, which would typically handle 60Hz and below. They blocked the reflex ports to effectively make them sealed enclosures. Not optimum output at 10Hz, but significant.

Sorry for taking the thread off topic!
 

DirtyLude

Well-Known Member
AD9833 is pretty much a one chip limited functionality function generator. Looked at the datasheet and all it says is the maximum frequency. One place says down to 1 HZ, though, so it should be good. Verufy, though.

Fleabay has modules for sale probably cheaper than the individual chips.
 
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