Nimrod82
Newbie level 3
Hi,
I'm working on an frequency adjustable sine wave oscillator, it comprises 2 555 timers, 1 8th order bessel LPF, a 5V voltage regulator and a 9V battery.
1 timer is used to generate a 280 Hz square wave with a 50% duty cycle, running this output through the LPF will give me a sine wave. The LPF takes in 5V as its power supply, and its cutoff frequency is determined by a clock(fclk=100*fo), that brings me to making the 2nd timer to generate a 30KHz square wave with a 50% duty cycle for fo=300 Hz.
so far I only have the timers on hand, when I use different DC sources and grounds for them, they do what they're suppose to do with a +-few% tolerances(280 Hz and 29KHz). When I use the same +25V DC source and ground for both of the timers, the frequency becomes very unstable(not what it is suppose to be), and the +25V DC source is limited to at around 8.8V no matter how much I turn the knob for the amplitude.
Is anyone familiar with this kind of problem? Thanks in advance!
I'm working on an frequency adjustable sine wave oscillator, it comprises 2 555 timers, 1 8th order bessel LPF, a 5V voltage regulator and a 9V battery.
1 timer is used to generate a 280 Hz square wave with a 50% duty cycle, running this output through the LPF will give me a sine wave. The LPF takes in 5V as its power supply, and its cutoff frequency is determined by a clock(fclk=100*fo), that brings me to making the 2nd timer to generate a 30KHz square wave with a 50% duty cycle for fo=300 Hz.
so far I only have the timers on hand, when I use different DC sources and grounds for them, they do what they're suppose to do with a +-few% tolerances(280 Hz and 29KHz). When I use the same +25V DC source and ground for both of the timers, the frequency becomes very unstable(not what it is suppose to be), and the +25V DC source is limited to at around 8.8V no matter how much I turn the knob for the amplitude.
Is anyone familiar with this kind of problem? Thanks in advance!