# Voltage Controlled Oscillator 0-5v 100Hz-3khz

## Was my question simple to understand and to the point (for future questions)

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#### GM_Quarenten

Joined Mar 3, 2010
3
Hi
i would like to build a voltage controlled oscillator
i want the input voltage to be able to take 0-5 volts
i want the output frequency to be between 100Hz and 3kHz
so,
0v = 100Hz
1V = 600 Hz
2v = 1200 Hz
3v = 1800 Hz
4v = 2400 Hz
5v = 3000 Hz

the output frequency could be a linear relationship or a logarithmic one i don't mind, the part above is just an example.
my question is.
How do i design this as simple as possible, could a 555 timer do it?, or a schmitt trigger oscillator?
and how
would it be possible for someone to link or give me a circuit diagram with the formulas to use to design this ? XD

(side note.. by all means any amplitude output is fine, can be ether sine wave or triangle or square wave.)
its the input and output design i am having trouble with.

ultimately*
i would like to hook the output to a 100-200mV microphone so i can listen to the output on my PC.

circuits i have looked at but i don't understand
1. http://en.wikipedia.org/wiki/File:VCO.jpg
2. http://www.ee.iitm.ac.in/vlsi/courses/ec330_2009/oscillator

cheers in advance, i would much appreciate any HELP!

#### MrChips

Joined Oct 2, 2009
29,865
Try LM566.

#### GM_Quarenten

Joined Mar 3, 2010
3
Thank you for the ideas
i am very grateful for the help : )
ill see if i can figure something out within the week.

#### iONic

Joined Nov 16, 2007
1,656
You could also take a look at Linear Technology - LTC6990

Last edited:

#### GM_Quarenten

Joined Mar 3, 2010
3

#### bertus

Joined Apr 5, 2008
22,233
Hello,

The +32p is the internal capacitance of the 4046.
This 32 picoFarad will not have many influecne at the low frequencies you are using.

Bertus

#### Audioguru

Joined Dec 20, 2007
11,248
The datasheets of the LM324 (quad opamp) and the LM358 (dual opamp) show a simple VCO circuit:

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