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

Discussion in 'The Projects Forum' started by GM_Quarenten, Oct 8, 2011.

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

1 vote(s)
100.0%

0 vote(s)
0.0%

0 vote(s)
0.0%
1. GM_Quarenten Thread Starter New Member

Mar 3, 2010
3
0
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!

2. MrChips Moderator

Oct 2, 2009
12,624
3,451
Try LM566.

Apr 5, 2008
15,799
2,385
Last edited: Oct 9, 2011
4. GM_Quarenten Thread Starter New Member

Mar 3, 2010
3
0
Thank you for the ideas
i am very grateful for the help : )
ill see if i can figure something out within the week.

5. iONic AAC Fanatic!

Nov 16, 2007
1,422
68
You could also take a look at Linear Technology - LTC6990

Last edited: Oct 11, 2011
6. GM_Quarenten Thread Starter New Member

Mar 3, 2010
3
0
Hi Bertus
sorry i dont understand what the +32P part of the formula is.
Fmin = 1 / R2 (C + 32p )
Fmax = Fmin + 1 / R1 (C + 32p )
i tried reading the data sheet but failed to gain any better understanding.
cheers

Apr 5, 2008
15,799
2,385
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

8. Audioguru New Member

Dec 20, 2007
9,411
896
The datasheets of the LM324 (quad opamp) and the LM358 (dual opamp) show a simple VCO circuit:

File size:
29.2 KB
Views:
287