very very VERY lof frequency generator

[jumpjack]

I'd need to generate an electric signal 12 Vpp and 0.001 Hertz or less.
How could I accomplish this without buying an expensive professional function generator?
I read about some Exar monolithic chips which handle low frequencies: does anybody know the code/name of one suitable for mHz or even uHz frequencies?

 

[carbonzit]

What kind of signal: sine wave? (No, it's not spelled "sign wave"!) square wave? sawtooth? triangle?

 

[Sceadwian]

What resolution? A simple DAC can easily do that, you just use a large prescaler from a timer to advance it.

 

[MrAl]

I can see a uC doing this too.

 

[jumpjack]

What kind of signal: sine wave? (No, it's not spelled "sign wave"!) square wave? sawtooth? triangle?

Actually I don't care, I have to perform some test.

@mrAl, which uC do you suggest?

 

[atferrari]

Most if not all could do it...

18F4431
18F452
18F4550
18F4585

Anyone of the above could do it easily (I used all of them, that's why).

Sure that the kind of signal does not matter? If so, go for a triangle. At such a low frequency you could "see" the signal with a multimeter (kind of boring have to say...)

 

[Sceadwian]

Actually I don't care, I have to perform some test.

And you don't know what the shape of the waveform needs to be? How can that be? It's critically important to answering your question so you BETTER know!

 

[trash]

DDS is the answer ... though not knowing what waveform is a bit unusual.
A nice big arse 1F supercap and/or inductor, should help smooth out those nasty little high frequency quantisation chirps.

It could even be done with sigma-delta modulation from something tiny like a 12F508. But even that's a bit of overkill.

 

[jumpjack]

Unfortunately this is all I know:

**broken link removed**

**broken link removed**

I have the lamp, now I need to generate the ELF electric field.

 

[jumpjack]

I wonder if, being frequency so low, I can generate it by hand by triggering a potenziometer...
1 mHz means 500 seconds (around 10 minutes) to go from +Vpp to -Vpp

But can we talk about "frequency" while voltage is just changing from +Vpp to -Vpp?

 

[ericgibbs]

I wonder if, being frequency so low, I can generate it by hand by triggering a potenziometer...
1 mHz means 500 seconds (around 10 minutes) to go from +Vpp to -Vpp

But can we talk about "frequency" while voltage is just changing from +Vpp to -Vpp?

Hi,
Is this related to Gravity control experiments.?

You could gear right down a small DC motor an use it as a ELF generator, hand crank it for example.?

 

[jumpjack]

Hi,
Is this related to Gravity control experiments.?

You could gear right down a small DC motor an use it as a ELF generator, hand crank it for example.?

I thought about it, but I think I couldn't get much precision in voltage this way...

 

[ericgibbs]

I thought about it, but I think I couldn't get much precision in voltage this way...

Why not, if you used a simple alternator setup , driven from a geared down DC motor , who's speed you could control..??

The output of the alternator into a op amp say, to give the 12Vac at .001Hz .??

 

[jumpjack]

Why not, if you used a simple alternator setup , driven from a geared down DC motor , who's speed you could control..??

The output of the alternator into a op amp say, to give the 12Vac at .001Hz .??

Probably in this case it would work, but it would become a "complex" system again.
A potentiometer in a voltage divider would be simpler but it would be more precise than manually moving a DC motor to generate current (I guess)

 

[ericgibbs]

Probably in this case it would work, but it would become a "complex" system again.
A potentiometer in a voltage divider would be simpler but it would be more precise than manually moving a DC motor to generate current (I guess)

I think problem with a manual system , would be producing a Sine wave.

 

[jumpjack]

I think problem with manual, would producing Sine wave.

Is it Gravity related.??

Who knows?

 

[ericgibbs]

Who knows?

I would suggest that for any experiment, its important that its repeatable, thats why I think a known frequency etc is needed.

 

[Sceadwian]

I'm with Eric 100%, such slap dasher is a gimick, if you don't control with at LEAST a known set of parameters and variances then there is no science occurring. You might as well be banging your head on the wall. If you seriously are interested in experimentation regardless of what it is about I can accept that, but not with such a cavalier attitude. The greatest discoveries of our time came from meticulous experimentation not just randomness, the discoveries were often triggered by unexpected results, but the control of the complete system is what lead to control over what was truly occurring.

 

[jumpjack]

good point.
thanks.

 

[trash]

No.. You've misread the information. MHz = A million cycles per second.
1MHz means 1,000,000 times or 500nS period to go from +Vpp to -Vpp

0.1MHz = 100KHz. Even most audio oscillators circuits will run as high as 100KHz to 1MHz with a few minor changes in components.