Voltage controlled Sin Wave oscillator for HZ

[umesh49]

Hi,
I am working on a project for which I need to generate two sin wave signal with 1F and 6F frequencies . F can change from 5HZ - 150Hz.
I thought to use some VCOs in combination voltage gain ckts to achieve this but could not find a Sin VCO to work in HZ frequency range.
I don't need Sin wave to put perfect and any phase lag between 1F and 6F will work for me. Remember, I want change both the frequency with some single voltage input or some single resistor change.
Please let me know if any one have an idea about some ICs which can help me. Any input will be helpful.

Thanks in Advance,
Umesh

 

[chuckey]

The problem with the 5 HZ is that of settling time. i.e. how long it will take for the output to settle at its correct level and frequency. You do not say how fast the change of frequency will be, i.e. 5-150 HZ in one second, 10 seconds. . . or how accurate the sine waves must be i.e. less then .01% THD, 1%?, 3 %?
One way to make a precision generator would be to have a fixed 100 KHZ oscillator , mix this with a variable 100,005 -> 100,150 HZ oscillator, filter the results using a LPF with a cut off at 50K HZ will give you the basic 5- 150 HZ variable. using a sniff of the oscillators, multiply them both by X6 ( X3 first then X2), a second mixer, identical LPF will give the X6 output. Because the change of frequencies are so low compared to the RF frequencies they are generated at, the levels will be flat. The mixers should give you less then .1 % THD.
Frank

 

[FvM]

There's nothing said about exact frequency respectively phase relation of both output signals. Thus I presume you are not talking about a PLL design.

The last analog function generator chip I'm aware of, XR2206 has been recently discontiued, but is still on stock at some catalog distributors and DIY shops. It's obvious, that this class of analog chips has been effectively superseeded by digital signal generators, particularly DDS chips.

Analog sine generators can be always designed following a straightforward analog behavioral modelling scheme. The well-known double integrator oscillator can be combined with analog multipliers or other variable gain elements to make up a VCO.

 

[umesh49]

Thanks Chuckey, Thanks FvM
My 1F frequency can change from 5Hz - 150Hz in 3 seconds. Actually it is getting generated by a electrical motors and magmatic field. It will depend upon RPM. Now same motor generates an 6F signal also again depend on same RPM. I was trying to simulate these signals using some hardware. Even a 10% THD shall work for me.

 

[FvM]

Did you consider, that a signal in the intended frequency range can be perfectly generated by a computer audio output? It can be defined in an audio file (e.g. using a free wave editing tool) and replayed afterwards.

 

[umesh49]

Did you consider, that a signal in the intended frequency range can be perfectly generated by a computer audio output? It can be defined in an audio file (e.g. using a free wave editing tool) and replayed afterwards.

Thats sound fascinating. This is new piece of information, thanks for this. I did find some literature and software to do the same. I got some option of Matlab programming. I don't have Matlab so searching for some VB based method. I am positive to find some way. Please let me know if you have some information.

Umesh

 

[FvM]

I didn't consider Matlab, but yes it has a soundcard driver as far a know. I would also think about writing your own C++ (or whatever programming language you prefer) application that generates the signals.

 

[umesh49]

Hi FVM,
Just to share. I found a software which can generate a single/mixed sin wave output. I used it and it worked for me.
Please follow the link : https://www.nch.com.au/tonegen/index.html

Thanks & Regards,
Umesh

 

[pplus]

Hi FVM,
Just to share. I found a software which can generate a single/mixed sin wave output. I used it and it worked for me.

Just to share.

Visual Analyser Project