hi,I do not need a precise VCO, actually I want to control the frequency by the help of R2R (ladder network), where the digital input value will increase/decrease the DC voltage of R2R network, so the frequency may be varied from 1Hz to 5Khz (i.e. My desired frequency). So what should I do?
I misunderstood. Varying the frequency of a simple 555 astable by varying voltage doesn't work very well, but varying frequency by changing resistance in the timing network can work quite well.I do not need a precise VCO, actually I want to control the frequency by the help of R2R (ladder network), where the digital input value will increase/decrease the DC voltage of R2R network, so the frequency may be varied from 1Hz to 5Khz (i.e. My desired frequency). So what should I do?
Fig 10 in the subject link has nothing to do with a VCOGo here: 555 Timer/Oscillator Tutorial
Scroll down until you find fig. 10. It's a little complex, but it allows wide freq variation and maintains 50% duty cycle, or 1:1 mark/space as our British friends say![]()
I think you could do it easy enough with a 2 transistor multivibrator.I do not need a precise VCO, actually I want to control the frequency by the help of R2R (ladder network), where the digital input value will increase/decrease the DC voltage of R2R network, so the frequency may be varied from 1Hz to 5Khz (i.e. My desired frequency). So what should I do?
The best I could get was about a 10:1 frequency range, varying the "CV" pin from near ground to near Vss. The duty cycle does not stay the same....Did you try simply using the 'control voltage' input? That's what it does, it varies the frequency as the voltage changes.